Confounding Roles of ER Stress and the Unfolded Protein Response in Skeletal Muscle Atrophy

Skeletal muscle is an essential organ, responsible for many physiological functions such as breathing, locomotion, postural maintenance, thermoregulation, and metabolism. Interestingly, skeletal muscle is a highly plastic tissue, capable of adapting to anabolic and catabolic stimuli. Skeletal muscle contains a specialized smooth endoplasmic reticulum (ER), known as the sarcoplasmic reticulum, composed of an extensive network of tubules. In addition to the role of folding and trafficking proteins within the cell, this specialized organelle is responsible for the regulated release of calcium ions (Ca²⁺) into the cytoplasm to trigger a muscle contraction. Under various stimuli, such as exercise, hypoxia, imbalances in calcium levels, ER homeostasis is disturbed and the amount of misfolded and/or unfolded proteins accumulates in the ER. This accumulation of misfolded/unfolded protein causes ER stress and leads to the activation of the unfolded protein response (UPR). Interestingly, the role of the UPR in skeletal muscle has only just begun to be elucidated. Accumulating evidence suggests that ER stress and UPR markers are drastically induced in various catabolic stimuli including cachexia, denervation, nutrient deprivation, aging, and disease. Evidence indicates some of these molecules appear to be aiding the skeletal muscle in regaining homeostasis whereas others demonstrate the ability to drive the atrophy. Continued investigations into the individual molecules of this complex pathway are necessary to fully understand the mechanisms.     

Infrared Image Processing to Guide the Identification of Damage and Dissipative Mechanisms in 3D Layer-to-Layer Woven Composites

Applied Composite Materials - This article discusses techniques that aim at facilitating the identification of dissipative mechanisms activated in woven composites under cyclic loadings. The focus...     

Trace element distributions between matte and slag in direct nickel matte smelting

ABSTRACT

Behaviour of trace elements in the nickel matte smelting was studied at 1673 K (1400°C) by equilibration-quenching techniques followed by direct phase analyses using electron probe X-ray microanalysis and laser ablation-inductively coupled plasma-mass spectrometry. The matte-slag samples at silica saturation were equilibrated with SO₂-CO-CO₂-Ar mixtures of fixed p_SO2, p_S2 and p_O2 in order to obtain a pre-determined oxidation degree for the sulphide matte, and thus to generate a targeted iron concentration of the nickel-copper–iron sulphide matte (Ni:Cu = 5, w/w), depending on the slag chemistry. The slag composition was varied from 0 to 2 wt-% K₂O and 0–10 wt-% MgO in silica saturation. The studied trace elements were Co, Ge, Pb, Se and Sn, but also the matte-to-slag distributions of the slag forming fluxing components Mg (MgO) and Si (SiO₂) were determined experimentally. Selenium was the only trace element studied which strongly enriched in the low-iron nickel mattes, and the deportment became larger when the sulphide matte depleted with iron. All the other trace elements behaved in the opposite way.     

Using 3D modeling and remote sensing capabilities for a better understanding of spatio-temporal heterogeneities of phytoplankton abundance in large lakes

Lake biological parameters show important spatio-temporal heterogeneities. This is why explaining the spatial patchiness of phytoplankton abundance has been a recurrent ecological issue and is an essential prerequisite for objectively assessing, protecting and restoring freshwater ecosystems. The drivers of these heterogeneities can be identified by modeling their dynamics. This approach is useful for theoretical and applied limnology. In this study, a 3D hydrodynamic model of Lake Geneva (France/Switzerland) was created. It is based on the Delft3D suite software and includes the main tributary (Rhône River) and two-dimensional high-resolution meteorological forcing. It provides 3D maps of water temperature and current velocities with a 1?h time step on a 1?km horizontal grid size and with a vertical resolution of 1?m near the surface to 7?m at the bottom of the lake. The dynamics and the drivers of phytoplankton heterogeneities were assessed by combining the outputs of the model and chlorophyll-a concentration (Chl-a) data from MERIS satellite images between 2008 and 2012. Results highlight physical mechanisms responsible for the occurrence of seasonal hot-spots in phytoplankton abundance in the lake. At the beginning of spring, Chl-a heterogeneities are usually caused by an earlier onset of phytoplankton growth in the shallowest and more sheltered areas; spatial differences in the timing of phytoplankton growth can be explained by spatial variability in thermal stratification dynamics. In summer, transient and locally higher phytoplankton abundances are observed in relation to the impact of basin-scale upwelling.     

Increasing the Efficiency of Organic Dye‐Sensitized Solar Cells over 10.3% Using Locally Ordered Inverse Opal Nanostructures in the Photoelectrode

3D inverse opal (3D‐IO) oxides are very appealing nanostructures to be integrated into the photoelectrodes of dye‐sensitized solar cells (DSSCs). Due to their periodic interconnected pore network with a high pore volume fraction, they facilitate electrolyte infiltration and enhance light scattering. Nonetheless, preparing 3D‐IO structures directly on nonflat DSSC electrodes is challenging. Herein, 3D‐IO TiO₂ structures are prepared by templating with self‐assembled polymethyl methacrylate spheres on glass substrates, impregnation with a mixed TiO₂:SiO₂ precursor and calcination. The specific surface increases from 20.9 to 30.7 m² g^?1 after SiO₂ removal via etching, which leads to the formation of mesopores. The obtained nanostructures are scraped from the substrate, processed as a paste, and deposited on photoelectrodes containing a mesoporous TiO₂ layer. This procedure maintains locally the 3D‐IO order. When sensitized with the novel benzothiadiazole dye YKP‐88, DSSCs containing the modified photoelectrodes exhibit an efficiency of 10.35% versus 9.26% for the same devices with conventional photoelectrodes. Similarly, using the ruthenium dye N719 as sensitizer an efficiency increase from 5.31% to 6.23% is obtained. These improvements originate mainly from an increase in the photocurrent density, which is attributed to an enhanced dye loading obtained with the mesoporous 3D‐IO structures due to SiO₂ removal.     

Assembly and Characterizations of Bifunctional Fluorescent and Magnetic Microneedles With One Decade Length Tunability

This report presents the fabrication of bifunctional magnetic and fluorescent microneedles (µNDs) made of a ternary mixture of magnetic nanoparticles (NPs), quantum dots (QDs), and polyelectrolyte. The assembly relies on the electrostatic complexation of negatively charged NPs with positively charged polymer strands and is controlled by the charge ratio between the nanoparticle building blocks and the polymer mortar. The resulting 1D objects can be actuated using an external magnetic field and can be imaged using fluorescence microscopy, thanks to the fluorescent and superparamagnetic properties inherited from their NP constituents. Using a combination of core and surface characterizations and a state‐of‐the‐art image analysis algorithm, the dependence of the brightness and length on the ternary composition is thoroughly investigated. In particular, statistics on hundreds of µNDs with a range of compositions show that the µNDs have a log‐lormal length distribution and that their mean length can be robustly tuned in the 5–50 µm range to match the relevant length scales of various applications in micromixing, bioassays or biomechanics.