Insects provide tractable models for enhancing our understanding of the physiological and cellular processes that enable survival at extreme low temperatures. They possess three main strategies to ...survive the cold: freeze tolerance, freeze avoidance or cryoprotective dehydration, of which the latter method is exploited by our model species, the Arctic springtail Megaphorura arctica, formerly Onychiurus arcticus (Tullberg 1876). The physiological mechanisms underlying cryoprotective dehydration have been well characterised in M. arctica and to date this process has been described in only a few other species: the Antarctic nematode Panagrolaimus davidi, an enchytraied worm, the larvae of the Antarctic midge Belgica antarctica and the cocoons of the earthworm Dendrobaena octaedra. There are no in-depth molecular studies on the underlying cold survival mechanisms in any species.
A cDNA microarray was generated using 6,912 M. arctica clones printed in duplicate. Analysis of clones up-regulated during dehydration procedures (using both cold- and salt-induced dehydration) has identified a number of significant cellular processes, namely the production and mobilisation of trehalose, protection of cellular systems via small heat shock proteins and tissue/cellular remodelling during the dehydration process. Energy production, initiation of protein translation and cell division, plus potential tissue repair processes dominate genes identified during recovery. Heat map analysis identified a duplication of the trehalose-6-phosphate synthase (TPS) gene in M. arctica and also 53 clones co-regulated with TPS, including a number of membrane associated and cell signalling proteins. Q-PCR on selected candidate genes has also contributed to our understanding with glutathione-S-transferase identified as the major antioxdidant enzyme protecting the cells during these stressful procedures, and a number of protein kinase signalling molecules involved in recovery.
Microarray analysis has proved to be a powerful technique for understanding the processes and genes involved in cryoprotective dehydration, beyond the few candidate genes identified in the current literature. Dehydration is associated with the mobilisation of trehalose, cell protection and tissue remodelling. Energy production, leading to protein production, and cell division characterise the recovery process. Novel membrane proteins, along with aquaporins and desaturases, have been identified as promising candidates for future functional analyses to better understand membrane remodelling during cellular dehydration.
The European corn borer, Ostrinia nubilalis Hbn., is a pest Lepidopteran species whose larvae overwinter by entering diapause, gradually becoming cold-hardy. To investigate metabolic changes during ...cold hardening, activities of four metabolic enzymes - citrate synthase (CS), lactate dehydrogenase (LDH), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured in whole-body homogenates of pupae, non-diapausing and diapausing larvae acclimated to 5 °C, -3 °C and -16 °C. The highest CS activity was detected in non-diapausing larvae, reflecting active development, while the highest in vitro LDH activity was recorded in diapausing larvae at temperatures close to 0 °C, evidencing a metabolic switch towards anaerobic metabolism. However, in-gel LDH activity showed that production of pyruvate from lactate is triggered by sub-zero temperatures. The activities of both aminotransferases were highest in non-diapausing larvae. Our findings suggest that during diapause and cold hardening the aminotransferases catalyse production of L-alanine, an important cryoprotectant, and L-aspartate, which is closely tied to both transamination reactions and Krebs cycle. The results of this study indicate that, during diapause, the activity of metabolic enzymes is synchronized with exogenous factors, such as temperatures close to 0 °C. These findings support the notion that diapause is metabolically plastic and vibrant, rather than simply a passive, resting state.
Fatigue crack paths in light aircraft wing spars Grbović, Aleksandar; Kastratović, Gordana; Sedmak, Aleksandar ...
International journal of fatigue,
June 2019, 2019-06-00, 20190601, Letnik:
123
Journal Article
Recenzirano
•Different cracks paths in three different wing spar designs are analysed.•Numerical analysis was carried out and results were verified using experimental data.•Integral spar was optimized using ...fatigue life as criterion.•Crack propagation simulation was carried out using XFEM.•Results provided better understanding of multiple cracks growth in 3D structures.
Different cracks paths in three different wing spar designs are analysed (differential, integral and optimized integral) to explore how those cracks paths affect fatigue life estimation. First, numerical analysis was carried out and verified, using the experimental data for differential wing spar, followed by numerical analysis of both optimized integral wing spars. The optimized integral spar was obtained by analysing three different cross-sections regarding fatigue life. Crack propagation simulation and fatigue life estimation were carried out by the extended finite element method, using Morfeo/Crack for Abaqus. Results provided better understanding and prediction of multiple cracks propagation in 3D structures.
In this study, an (1)H-NMR -based metabolomic approach was used to investigate the biochemical mechanisms of diapause and cold hardiness in diapausing larvae of the European corn borer Ostrinia ...nubilalis. Metabolomic patterns in polar hemolymph extracts from non-diapausing and diapausing larvae of O. nubilalis were compared. Analysis indicated 13 metabolites: 7 amino acids, glycerol, acetate, citrate, succinate, lactate and putrescine. Results show that diapausing larvae display different metabolomic patterns compared to active non-diapausing larvae, with predominant metabolites identified as glycerol, proline and alanine. In specific diapausing larvae initially kept at 5 °C then gradually chilled to –3 °C and –16 °C, alanine , glycerol and acetate were predominant metabolites. (1)H-NMR spectroscopy provides new insight into the metabolomic patterns associated with cold resistance and diapause in O. nubilalis larvae, suggesting distinct metabolomes function in actively developing and diapausing larvae.
This paper proposes a novel advanced distribution management system (ADMS) solution based on a common operation technology platform implemented on a cloud infrastructure. It introduces a ...virtualization methodology that is used to transition and deploy a traditional, monolithic ADMS in a cloud environment. First, typical ADMS functional blocks (FBs) are identified and their performance is evaluated with respect to four major metrics: processor, memory, network, and storage utilization. Next, a cloud infrastructure-based ADMS solution is presented, based on a collection of FBs mapped to a set of virtual machines. Finally, the proposed architecture is validated via deployment on a physical hardware platform with two representatively sized distribution networks and emulated workloads. Obtained results show that an ADMS, as a mission-critical system, can be deployed on a cloud infrastructure, providing many benefits of virtualized solutions, without negative impact on system performance.
A new organic blue‐light emitter 1‐methyl‐2‐(anthryl)‐imidazo4,5‐f1,10‐phenanthroline (1) has been synthesized and fully characterized. The utility of compound 1 as a blue‐light emitter in ...electroluminescent (EL) devices has been evaluated by fabricating a series of EL devices A where compound 1 functions as an emitter. The EL spectrum of device series A has the emission maximum at 481 nm with the CIE (Commission Internationale de l'Eclairage) color coordinates 0.198 and 0.284. The maximum luminance of devices in series A is 4000 cd m–2 and the best external quantum efficiency of device series A is 1.82 %. The utility of compound 1 as an electron injection–electron transport material has been evaluated by constructing a set of EL devices B where 1 is used as either the electron‐injection layer or the electron injection–electron transport layer. The performance of device series B is compared to the standard device in which Alq3 (tris(8‐hydroxyquinoline) aluminum) is used as the electron injection–electron transport layer. The experimental results show that the performance of 1 as an electron injection–electron transport material is considerably better than Alq3. The stability of device series B is comparable to that of the standard Alq3 device. The excellent performance of 1 as an electron injection/transport material may be attributed to the strong intermolecular interactions of 1 in the solid state as revealed by single‐crystal X‐ray diffraction analysis. In addition, compound 1 is a colorless material with a much larger highest occupied molecular orbital–lowest unoccupied molecular (HOMO–LUMO) gap than Alq3, which renders it potentially useful for a wide range of applications in EL devices.
Efficient electron‐transport materials are important for the development of high‐performance organic light‐emitting diodes. The title compound, a colorless organic molecule with strong intermolecular interactions (see Figure), is shown to be a bright blue‐light emitter and a highly efficient electron‐transport material in electroluminescent devices.
Representation of quantum states by statistical ensembles on the quantum phase space in the Hamiltonian form of quantum mechanics is analyzed. Various mathematical properties and some physical ...interpretations of the equivalence classes of ensembles representing a mixed quantum state in the Hamiltonian formulation are examined. In particular, non-uniqueness of the quantum phase space probability density associated with the quantum mixed state, Liouville dynamics of the probability densities and the possibility to represent the reduced states of bipartite systems by marginal distributions are discussed in detail. These considerations are used to study ensembles of hybrid quantum-classical systems. In particular, nonlinear evolution of a single hybrid system in a pure state and unequal evolutions of initially equivalent ensembles are discussed in the context of coupled hybrid systems.
Motor skill learning and neuro-rehabilitation Burdet, E; Sanguineti, V; Heuer, H ...
IEEE transactions on neural systems and rehabilitation engineering
20, Številka:
3
Journal Article
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