Papers by Keyword: Microparticles

Abstract: The small size and large surface area of nano and microparticles are interesting properties for drug delivery, hypothetically capable of overcoming some limitations of conventional therapeutic medicine and diagnostic agents. Although their features are highly influenced by the polymer characteristics, these particles are known for encapsulating high amounts of drugs, improving their stability and bioavailability and enabling different administration routes. Among synthetic polymers, polycaprolactone (PCL) nanoparticles are widely studied in drug delivery due to the polymer excellent biocompatibility and degradability and for its ability to blend with other polymers. On its turn, among natural polymers, glucan has been emerging as a promising candidate for drug delivery particularly due to structure forming abilities and its immunomodulatory effects. Under the safe-by-design approach for the development of polymeric particles, this review encloses a comprehensive summary of production methods, physicochemical characteristics and immunotoxicity profiles of PCL and glucan particles developed for drug delivery.

Abstract: This study develops a fast and simple way to produce high purity magnetite (Fe₃O₄) microparticles from mill scale by using hydrogen reduction with the addition of vapour as a retarding agent. By optimising the reduction temperature and gas flow rate, the characterisations by X-ray diffractometry technique shown that the Fe₃O₄ fraction of over 93 wt.-% is shown at the reduction temperature of 550 – 650 oC with the flow rate of the 4.5-5.5 mol%H₂ + Ar gas + H₂O gas mixture from 100 – 200 ml/min. The highest Fe₃O₄ fraction of over 99 wt.-% can be achieved from the reduction with the mixed gas at 650 oC and the flow rate of 200 ml/min for 4 hour.

Abstract: The objective of this study was to investigate the effect of polymers and their content level on the taste-masking efficiency of spray-dried microparticles. Diclofenac sodium (DS) was used as a model drug, owing to its bitter taste. Hydroxypropyl methylcellulose F4M (HPMC F4M) and Eudragit^® E PO were involved in the study as a hydrophilic and a pH-responsive polymer, respectively. The taste-masked DS microparticles with the drug:polymer ratios of 1:1, 1:2 and 1:4 were prepared by the spray-drying technique. The collapsed hollow sphere HPMC F4M based-microparticles was observed meanwhile spray-dried Eudragit^® E PO based-microparticles were spherical. Loading capacity of both polymer based-microparticles decreased regarding to the increment of drug:polymer ratio. The Eudragit^® E PO based-microparticle in the ratio of 1:4 provided the highest loading efficiency as 91.97%. According to the simplified dissolution testing, the taste-masking ability of HPMC F4M and Eudragit^® E PO based-microparticles increased upon the increase of drug:polymer ratio. Drug release at the first 5 minutes from dissolution profiles, tested by type II dissolution apparatus, of the Eudragit^® E PO based-microparticles was delayed compared to HPMC F4M based-microparticles. Therefore, it could be assumed that Eudragit^® E PO was a promising taste-masking polymer for DS with a pleasant taste.

Abstract: This work investigates the effect of silica nanoparticles functionalized with poly-diallyldimethylammonium chloride (PDDA) and silica microparticle inclusions (1.0 wt% and 3.5 wt%) on the impact resistance of hybrid carbon fibre reinforced composite laminates (HCFRCs) and tensile modulus of particle reinforced polymers (PRPs) via Full-Factorial Design of Experiments. The data were analysed with Analysis of Variance (ANOVA). The inclusion of particles led to reduced impact absorption of HCFRCs, except for composites with 1.0 wt% of silica in microscale, which provides an increase of 11.75% in the impact resistance. Microstructural analysis of fractured impact samples revealed pull-out as the predominant fracture mode in 1.0 wt% silica microparticle composites. Such mechanism leads to impact energy dissipation which may explain the increased impact resistance of these samples.

Abstract: The first results of the research of the distribution of welding aerosol nano- and microparticles in the working area based on substance and morphological analysis are presented in the paper. A 3D-model of the welding aerosol cloud demonstrating the distribution of nano- and microparticles in the working area of the welder was created using the granulometric data of the samples. The most dangerous area with maximum density of nano- and microparticles of welding fumes was singled out: 1.3 m in height and 5 meters in all directions.Welding aerosol is a disperse system in which the solid component of the welding aerosol (SCWA) acts as the phase, and the mixture of gases (gaseous component of welding aerosol, or GCWA) – as the medium. SCWA stays suspended in the air for a long time spreading far beyond the working area of a welder [1].The aim of this work was to create a 3D-model of a welding aerosol cloud, demonstrating the spread of nano- and microparticles of welding aerosol in the working area of a welder. The 3D model was created using granulometric data of samples collected by the author’s method.

Abstract: We report on the structural characterization and the photovoltaic performances of novel photoelectric conversion materials fabricated by simplified and cheap procedures based on a chemical approach. Our prepared composite microparticles were composed of fluorosilicate/phosphorus oxide holding together by ammonium. When such composite microparticles were used in the active layer of the hybrid solar cells, the relatively high J_sc was obtained by causing the adequate carrier transport from the active layer to each electrode, attaining the best photovoltaic performance with a PCE of 4.45 %. These findings indicate that the fluorosilicate/phosphorus oxide composite microparticles have sufficient ability as the photoelectric conversion materials.

Abstract: The paper deals with modelling of the time varying electric field, applied to composites structures of inorganic materials (containing metal and metal oxide). The structural changes at the initials stages of sintering, characterised by the number of contact per particle and an increase of the areas of interparticle contact have been modelled and examined. The aim of study was estimation of the electric field strength, current density, power losses and forces, acting along the contact area between particles. The field models have been obtained using finite element method and QuickField 5.6 software package.

Abstract: Here, a novel biomimetic scaffold with controlled diameters and mechanical properties was prepared from negatively charged silk fiber (SF) and poly (lactide-co-glycolide) (PLGA) by electrospinning technique. The fiber diameters and mechanical properties of the scaffolds were controlled by varying the weight ratio of PLGA/SF. Furthermore, in order to promote endothelialization on the scaffolds, pEGFP-ZNF580 loaded microparticles (MPs) were used to modify the surface of the electrospun scaffolds via electrospraying technique. Results showed that the composite scaffolds with these MPs could promote proliferation and migration of EA.hy926 cells significantly.

Abstract: Ultrasonic standing wave (USW) manipulation of suspension microparticles separation has attracted wide attention due to its non-direct contact, being harmless to the particles, easy to manufacture, low energy consumption and high separation efficiency. USW is widely used in industrial processes, environmental assessment, biochemical analysis, clinical diagnosis and other fields. In this article, particles stress and movement process is analyzed, meanwhile, aggregation and separation of the particles is discussed respectively and the future direction of development is pointed out.

Abstract: Use of cored wire - shielding gas (gas mixture) pair, during mechanized MAG welding, causes the microparticles formation which is harmful for the welder’s health. The paper presents the experimental method for determining the concentration of the microparticles generated during MAG welding when rutile cored wires (standard and low fume emission) and metal powder cored wires (standard and low fume emission) are used. Carbon dioxide and the shielding gas mixture are investigated, too. Four types of cored wires were comparatively analysed, when three wire speed values were applied. The research of the microparticles concentration was conducted after each welding bead deposition, at the upper part of the welding enclosure, using MicroDust Pro particulate monitor. After each weld bead was deposited, the metal frame of the welding enclosure was removed, and, the fumes and gases, produced during the welding process, were eliminated through two fans, positioned inside and outside of the equipment. Using rutile cored wire with low fume emission, a decrease of microparticles concentration up to 30% is noticed in comparison with standard rutile cored wire. Using metal powders cored wire with low fume emission, the microparticles concentration is diminished with 12.5% comparing with standard metal powders cored wire.