Flow,suspension and mixing dynamics in DASGIP bioreactors,Part 2

This work aims to characterize the mixing and suspension dynamics occurring within two commercially available DASGIP bioreactor configurations, equipped with a two-blade paddle impeller with large impeller to tank diameter ratio, D/T = 0.97. Both continuous and intermittent agitation modes were employed to determine the impact that agitation strategy has upon mass transfer and microcarrier settling/suspension. This paper builds upon the flow dynamics data presented in Part 1 for a flat bottom DASGIP bioreactor and shows how intermittent agitation can break-up regions of slow mixing observed during continuous agitation, therefore substantially increasing the mixing efficiency of the system. Similarly, it was found that microcarrier characteristics might significantly affect the level of suspension when the impeller is in dwell status when intermittent agitation modes are used.     

Epileptic seizure detection using hybrid machine learning methods

Neural Computing and Applications - The aim of this study is to establish a hybrid model for epileptic seizure detection with genetic algorithm (GA) and particle swarm optimization (PSO) to...     

Bone Mass and Osteoblast Activity Are Sex-Dependent in Mice Lacking the Estrogen Receptor α in Chondrocytes and Osteoblast Progenitor Cells

While estrogen receptor alpha (ERα) is known to be important for bone development and homeostasis, its exact function during osteoblast differentiation remains unclear. Conditional deletion of ERα during specific stages of osteoblast differentiation revealed different bone phenotypes, which were also shown to be sex-dependent. Since hypertrophic chondrocytes can transdifferentiate into osteoblasts and substantially contribute to long-bone development, we aimed to investigate the effects of ERα deletion in both osteoblast and chondrocytes on bone development and structure. Therefore, we generated mice in which the ERα gene was inactivated via a Runx2-driven cyclic recombinase (ERα^{fl/fl; Runx2Cre}). We analyzed the bones of 3-month-old ERα^{fl/fl; Runx2Cre} mice by biomechanical testing, micro-computed tomography, and cellular parameters by histology. Male ERα^{fl/fl; Runx2Cre} mice displayed a significantly increased cortical bone mass and flexural rigidity of the femurs compared to age-matched controls with no active Cre-transgene (ERα^fl/fl). By contrast, female ERα^{fl/fl; Runx2Cre} mice exhibited significant trabecular bone loss, whereas in cortical bone periosteal and endosteal diameters were reduced. Our results indicate that the ERα in osteoblast progenitors and hypertrophic chondrocytes differentially contributes to bone mass regulation in male and female mice and improves our understanding of ERα signaling in bone cells in vivo.     

Neuroprotective Effect of Valproic Acid on Salicylate-Induced Tinnitus

High-dose salicylate induces temporary moderate hearing loss and the perception of a high-pitched tinnitus in humans and animals. Previous studies demonstrated that high doses of salicylate increase N-methyl-d-aspartate (NMDA) receptor levels, resulting in a rise in Ca²⁺ influx and induction of excitotoxicity. Glutamate excitotoxicity is associated with failure in the maintenance of calcium homeostasis, mitochondrial dysfunction, and production of reactive oxygen species (ROS). Valproic acid (VPA) is widely used for the management of bipolar disorder, epilepsy, and migraine headaches, and is known to regulate NMDA receptor activity. In this study, we examined the beneficial effects of VPA in a salicylate-induced tinnitus model in vitro and in vivo. Cells were pretreated with VPA followed by salicylate treatment. The expression levels of NMDA receptor subunit NR2B, phosphorylated cAMP response element-binding protein—an apoptosis marker, and intracellular levels of ROS were measured using several biochemical techniques. We observed increased expression of NR2B and its related genes TNFα and ARC, increased intracellular ROS levels, and induced expression of cleaved caspase-3. These salicylate-induced changes were attenuated in the neuronal cell line SH-SY5Y and rat cortical neurons after VPA pretreatment. Together, these results provide evidence of the beneficial effects of VPA in a salicylate-induced temporary hearing loss and tinnitus model.     

A Simple and Adaptive Methodology to Use a Commercial Solvent Extraction Microsystem as Screening Tool: Validation with the U-TBP Chemical System

The solvent extraction of a U (VI) present at several g.L^?1 from the aqueous phase [HNO₃] = 3 M to the organic one (30% TBP) involves a change of the viscosity of the two phases during the extraction process in microsystem. This shifts the position of the interface between the two phases and then affects the quality of the separation at the outlet of the microsystem. The aim of this study is to present a simple method to stabilize the quality of the separation by controlling the interface position during solvent extraction in microsystem. First, a study at low concentration is operated in order to set flow rates and contact time that allow optimal parallel flows and mass transfer. Second, the influence of the high grade concentration (up to 140 g.L^?1) of solute on the flows and extraction yield is studied.     

Biomimetic protein‐based elastomeric hydrogels for biomedical applications

In recent years, protein‐based elastomeric hydrogels have gained increased research interest in biomedical applications for their remarkable self‐assembly behaviour, tunable 3D porous structure, high resilience (elasticity), fatigue lifetime (durability), water uptake, excellent biocompatibility and biological activity. The proteins and polypeptides can be derived naturally (animal or insect sources) or by recombinant (bacterial expression) routes and can be crosslinked via physical or chemical approaches to obtain elastomeric hydrogels. Here we review and present the recent accomplishments in the synthesis, fabrication and biomedical applications of protein‐based elastomeric hydrogels such as elastin, resilin, flagelliform spider silk and their derivatives. © 2013 Society of Chemical Industry     

Near-Infrared Imaging Spectroscopy as a Tool to Discriminate Two Cryptic Tetramorium Ant Species

Correct species identification is a precondition for many ecological studies. Morphologically highly similar, i.e., cryptic, species are an important component of biodiversity but particularly difficult to discriminate and therefore understudied ecologically. To find new methods for their rapid identification, thus, is important. The cuticle's chemical signature of insects often is unique for species. Near-infrared spectroscopy (NIRS) can capture such signatures. Imaging NIRS facilitates precise positioning of the measurement area on biological objects and high-resolution spatial capturing. Here, we tested the applicability of imaging NIRS to the discrimination of cryptic species by using the ants Tetramorium caespitum and T. impurum. The classification success of Partial Least Squares Regression was 98.8%. Principal Component Analysis grouped spectra of some T. impurum individuals with T. caespitum. Combined with molecular-genetic and morphological evidence, this result enabled us to pose testable hypotheses about the biology of these species. We conclude that discrimination of T. caespitum and T. impurum with imaging NIRS is possible, promising that imaging NIRS could become a time- and cost-efficient tool for the reliable discrimination of cryptic species. This and the direct facilitation of potential biological insight beyond species identification underscore the value of imaging NIRS to ecology.