Tuning Alginate Microparticle Size via Atomization of Non-Newtonian Fluids

A new approach based on the atomization of non-Newtonian fluids has been proposed to produce microparticles for a potential inhalation route. In particular, different solutions of alginate were atomized on baths of different crosslinkers, piperazine and barium chloride, obtaining microparticles around 5 and 40 microns, respectively. These results were explained as a consequence of the different viscoelastic properties, since oscillatory analysis indicated that the formed hydrogel beads with barium chloride had a higher storage modulus (1000 Pa) than the piperazine ones (20 Pa). Pressure ratio (polymer solution-air) was identified as a key factor, and it should be from 0.85 to 1.00 to ensure a successful atomization, obtaining the smallest particle size at intermediate pressures. Finally, a numerical study based on dimensionless numbers was performed to predict particle size depending on the conditions. These results highlight that it is possible to control the microparticles size by modifying either the viscoelasticity of the hydrogel or the experimental conditions of atomization. Some experimental conditions (using piperazine) reduce the particle size up to 5 microns and therefore allow their use by aerosol inhalation.

Study results of the choice of barium salts reagents for wastewater treatment from sulfates

The research on the removal of sulfates from mine wastewater is presented in the article. A new purification method has been proposed that allows removing a significant part of sulfates by precipitation in the form of barium sulfate. The present studies were devoted to the removal of sulfates from mine wastewater with a sulfate content of 1050 mg/l by introducing various doses of barium-containing reagents, namely barium chloride, hydroxide and barium carbonate. Among the listed reagents, the best results were obtained, using barium chloride and hydroxide. The use of barium chloride with a dose of 2700 mg/l and barium hydroxide with a dose of 3200 mg/l made it possible to reduce the concentration of sulfates below the maximum permissible (100 mg/l) when discharged into a reservoir for fishery purposes. A reliable in operation technological scheme for removing sulfates from highly concentrated mine wastewater has been developed, which makes it possible to reduce sulfates in the treated waste liquid discharged into the reservoir to 100 mg/l and below. In this case, the purification is carried out with separation of streams - in a smaller part (about 26% of the incoming); barium chloride is introduced, in the second - barium hydroxide. After that, the streams are mixed again, settled, sent to the calciner and to the post-treatment facilities and discharged into the reservoir. The resulting sludge is stored in special landfills or is processed to extract valuable components.

Structural Characterization of Sulfated Polysaccharide Isolated From Red Algae (Gelidium crinale) and Antioxidant and Anti-Inflammatory Effects in Macrophage Cells

Gelidium crinale, the red algae belonging to Geliaceae Gelidium, is a traditional edible and industrial alga in China. A sulfated polysaccharide (GNP) is successfully separated from Gelidium crinale by acid extraction and two-step column chromatography. Chemical analysis showed that the molecular weight of GNP was 25.8 kDa and the monosaccharide composition had the highest galactose content and confirmed the presence and content (16.5%) of sulfate by Fourier transform infrared spectroscopy (FT-IR) spectrometry as well as barium chloride-gelatin methods. In addition, the effect of GNP on lipopolysaccharide (LPS)-induced oxidative stress and inflammation in macrophages was also evaluated. The research results showed that GNP had fairly strong scavenging activities on 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical, hydroxyl radical, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and had Fe2+-chelating ability in a dose-dependent manner. At the same time, it significantly inhibits the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and the production of pro-inflammatory cytokines in RAW 264.7 cells induced by LPS through blocking the mitogen-activated protein kinase (MAPK)/nuclear factor kappa beta (NF-κB) signaling pathway. These results indicate that GNP may be a latent component anti-inflammation in pharmaceutical and functional food industries.

Species dependent cardiac electrophysiological effects elicited by various potassium channel blocking drugs

Rodents are commonly used as models in electrophysiology. However, distinct differences exist between large animals and rodents in terms of their ion channel expression and action potential shapes, possibly limiting the translational value of findings obtained in rodents. We aimed for a direct comparison of the possible impact of selective inhibition of ion channels on the cardiac repolarization in preparations from human hearts and from model species. We applied the standard microelectrode technique at 37°C on cardiac ventricular preparations (papillary muscles and trabecules) from human (n = 63), dog (n = 47), guinea pig (n = 53), rat (n = 43), and rabbit (n = 16) hearts, paced at 1 Hz. To selectively block the IKur current, 1 µM XEN-D101; IK1 current, 10 µM barium chloride; IKr current, 50 nM dofetilide; IKs current, 500 nM HMR-1556; and Ito current, 100 µM chromanol-293B were applied directly to the tissue bath. The block of IKur and IK1 elicited significantly more prominent prolongation of APD in rats (35.6% and 67.9%, respectively) when compared with the other species, including that of human (1.0% and 2.6%, respectively). On the other hand, IKr block did not affect APD in rat preparations (1.6%), whereas it elicited marked prolongation in other species (9.0–47.7%), especially being pronounced in human preparations (60.3%). IKs inhibition elicited similar but minor APD prolongation (0.3–11.4%) in all species. Inhibition of Ito moderately lengthened APD in dog (22.3%) and rabbit (17.5%) preparations but elicited no change of APD in human preparations. In contrast, block of Ito caused marked APD prolongation in rat preparations (33.2%). Our findings suggest that the specific inhibition of various ion channels elicits fundamentally different effects in rodent ventricular action potential when compared with those of other species, including human. Therefore, from a translational standpoint, rodent models in cardiac electrophysiological and arrhythmia research should be used with great caution.

A Photo and Thermally Stimulated Luminescence Study of BaCl2:Eu2+ with Application to Neutron Imaging

<p>This thesis presents the results of a photo and thermally stimulated luminescence study of europium-doped barium chloride in relation to its potential application as a storage phosphor in glass ceramics for radiation imaging, particularly for neutron imaging. Previous work done on lithium borate (LiBO) glasses containing BaCl2:Eu2+ nanocrystals at Victoria University of Wellington had demonstrated comparable imaging capability with commercially available BaFBr:Eu2+ based imaging plates, though the sensitivity and spatial resolution were inferior to that material, and there was a substantial afterglow during the read-out process which degraded any image. These problems are addressed here. The effect of various different co-dopants on the storage properties was examined using the thermally stimulated luminescence (TSL) technique, with dopants primarily chosen from the alkali and alkaline earth elements. The resulting glow curves have been analysed to determine the activation energies associated with the various traps, and tentative assignments of structural defects to the various glow curve peaks are proposed. It was found that Li+ and Na+ gave small increases (20% and 50% respectively) in efficiency, though other dopants tended to reduce the overall output. In particular, K+ and Rb+ were found to substantially reduce the output efficiency. It was found that Li+ co-doped BaCl2:Eu2+ contained thermally unstable traps which at room temperature could result in the observed afterglow in LiBO/BaCl2 glass ceramics through a read-out induced phototransfer process. The experimental measurements required substantial hardware and software development of the existing VUW facilities for TSL, and these improvements are also described here. The most significant improvements are an extension of the operating range at the lower end of the existing TSL spectrometer to -50 degrees C through a cooled gas flow system, and the engineering of a completely new system to record TSL from 25 K to 400 K.</p>

A Photo and Thermally Stimulated Luminescence Study of BaCl2:Eu2+ with Application to Neutron Imaging

<p>This thesis presents the results of a photo and thermally stimulated luminescence study of europium-doped barium chloride in relation to its potential application as a storage phosphor in glass ceramics for radiation imaging, particularly for neutron imaging. Previous work done on lithium borate (LiBO) glasses containing BaCl2:Eu2+ nanocrystals at Victoria University of Wellington had demonstrated comparable imaging capability with commercially available BaFBr:Eu2+ based imaging plates, though the sensitivity and spatial resolution were inferior to that material, and there was a substantial afterglow during the read-out process which degraded any image. These problems are addressed here. The effect of various different co-dopants on the storage properties was examined using the thermally stimulated luminescence (TSL) technique, with dopants primarily chosen from the alkali and alkaline earth elements. The resulting glow curves have been analysed to determine the activation energies associated with the various traps, and tentative assignments of structural defects to the various glow curve peaks are proposed. It was found that Li+ and Na+ gave small increases (20% and 50% respectively) in efficiency, though other dopants tended to reduce the overall output. In particular, K+ and Rb+ were found to substantially reduce the output efficiency. It was found that Li+ co-doped BaCl2:Eu2+ contained thermally unstable traps which at room temperature could result in the observed afterglow in LiBO/BaCl2 glass ceramics through a read-out induced phototransfer process. The experimental measurements required substantial hardware and software development of the existing VUW facilities for TSL, and these improvements are also described here. The most significant improvements are an extension of the operating range at the lower end of the existing TSL spectrometer to -50 degrees C through a cooled gas flow system, and the engineering of a completely new system to record TSL from 25 K to 400 K.</p>