A study on pressure-driven gas transport in porous media: from nanoscale to microscale

Gas flow in porous media can be seen in various engineering devices such as catalytic converters and fuel cells. It is important to understand transport phenomena in porous media for improvement of the performance of such devices. Porous media with pores as small as the mean free path of gas molecules are used in such devices as proton exchange membrane fuel cells. It is difficult to measure molecular transport through such small pores in the experimental approach. In addition, even when using theoretical or numerical approaches, gas flow through nanoscale pores must be treated by the Boltzmann equation rather than the Navier–Stokes equations because it cannot be considered as a continuum. Thus, conventional analyses based on the continuum hypothesis are inadequate and the transport phenomena in porous media with nanoscale pores are not yet clearly understood. In this study, we represented porous media by randomly arranged solid spherical particles and simulated pressure-driven gas flow through the porous media by using the direct simulation Monte Carlo (DSMC) method based on the Boltzmann equation. DSMC simulations were performed for different porosities and different sizes of solid particles of porous media. It was confirmed that Darcy’s law holds even in the case of porous media with micro-/nanoscale pores. Using the obtained results, we constructed expressions to estimate the pressure-driven gas transport in porous media with micro-/nanoscale pores and porosity ranging from 0.3 to 0.5. The flow velocities estimated by using the constructed expressions agreed well with those obtained in the DSMC simulations.     

Anti-Kir4.1 Antibodies in Multiple Sclerosis: Specificity and Pathogenicity

The glial cells in the central nervous system express diverse inward rectifying potassium channels (Kir). They express multiple Kir channel subtypes that are likely to have distinct functional roles related to their differences in conductance, and sensitivity to intracellular and extracellular factors. Dysfunction in a major astrocyte potassium channel, Kir4.1, appears as an early pathological event underlying neuronal phenotypes in several neurological diseases. The autoimmune effects on the potassium channel have not yet been fully described in the literature. However, several research groups have reported that the potassium channels are an immune target in patients with various neurological disorders. In 2012, Srivastava et al. reported about Kir4.1, a new immune target for autoantibodies in patients with multiple sclerosis (MS). Follow-up studies have been conducted by several research groups, but no clear conclusion has been reached. Most follow-up studies, including ours, have reported that the prevalence of Kir4.1-seropositive patients with MS was lower than that in the initial study. Therefore, we extensively review studies on the method of antibody testing, seroprevalence of MS, and other neurological diseases in patients with MS. Finally, based on the role of Kir4.1 in MS, we consider whether it could be an immune target in this disease.     

Ambient pressure synthesis of La2LiHO3 as a solid electrolyte for a hydrogen electrochemical cell

The capability of La₂LiHO₃ as a H⁻ conductive solid electrolyte has recently been demonstrated, which has suggested the possibility of developing electrochemical devices based on H⁻ conduction. However, the performance of La₂LiHO₃ as a solid electrolyte has not yet been fully clarified. In this study, we prepared La₂LiHO₃ sintered pellets by a conventional solid-state reaction with LiH flux under ambient pressure and characterized the crystal structure and thermal stability (to moisture, ambient air, and oxygen) by neutron and X-ray diffraction measurements. The produced sintered pellets exhibited an activation energy of 69.2 kJ/mol, which is consistent with the value of the sample synthesized by the high-pressure method. The gas-sealing properties of the sintered La₂LiHO₃ pellets as the H⁻ conductive solid electrolyte were confirmed by measuring the electromotive force using a hydrogen concentration cell.     

Current Management and Therapeutic Strategies for Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is characterized by accumulation of amyloid β (Aβ) in walls of leptomeningeal vessels and cortical capillaries in the brain. The loss of integrity of these vessels caused by cerebrovascular Aβ deposits results in fragile vessels and lobar intracerebral hemorrhages. CAA also manifests with progressive cognitive impairment or transient focal neurological symptoms. Although development of therapeutics for CAA is urgently needed, the pathogenesis of CAA remains to be fully elucidated. In this review, we summarize the epidemiology, pathology, clinical and radiological features, and perspectives for future research directions in CAA therapeutics. Recent advances in mass spectrometric methodology combined with vascular isolation techniques have aided understanding of the cerebrovascular proteome. In this paper, we describe several potential key CAA-associated molecules that have been identified by proteomic analyses (apolipoprotein E, clusterin, SRPX1 (sushi repeat-containing protein X-linked 1), TIMP3 (tissue inhibitor of metalloproteinases 3), and HTRA1 (HtrA serine peptidase 1)), and their pivotal roles in Aβ cytotoxicity, Aβ fibril formation, and vessel wall remodeling. Understanding the interactions between cerebrovascular Aβ deposits and molecules that accumulate with Aβ may lead to discovery of effective CAA therapeutics and to the identification of biomarkers for early diagnosis.     

A lithium superionic conductor

Batteries are a key technology in modern society. They are used to power electric and hybrid electric vehicles and to store wind and solar energy in smart grids. Electrochemical devices with high energy and power densities can currently be powered only by batteries with organic liquid electrolytes. However, such batteries require relatively stringent safety precautions, making large-scale systems very complicated and expensive. The application of solid electrolytes is currently limited because they attain practically useful conductivities (10(-2) S cm(-1)) only at 50-80 °C, which is one order of magnitude lower than those of organic liquid electrolytes. Here, we report a lithium superionic conductor, Li(10)GeP(2)S(12) that has a new three-dimensional framework structure. It exhibits an extremely high lithium ionic conductivity of 12 mS cm(-1) at room temperature. This represents the highest conductivity achieved in a solid electrolyte, exceeding even those of liquid organic electrolytes. This new solid-state battery electrolyte has many advantages in terms of device fabrication (facile shaping, patterning and integration), stability (non-volatile), safety (non-explosive) and excellent electrochemical properties (high conductivity and wide potential window).     

ERM proteins: head-to-tail regulation of actin-plasma membrane interaction

Viral infections due to hepatitis C virus in hemodialysis patients are frequent and have a potential risk of progression towards chronicity. Biochemical and viral markers of infection, are transaminases level, anti-HCV serology and the detection of HCV RNA, respectively. A rational strategy based on routine use of these three diagnostic tools is proposed in order to avoid unnecessary assays and to increase in the case of health cost control, the cost/efficacy ratio. The latter is set up, in the sero-negative hemodialysed, on the early detection of infection by the hepatitis C virus in order to consider of a therapeutic which is able to cure patients and to avoid the ineluctable passage towards chronicity; in hemodialysed with positive HCV serology, the detection of HCV RNA allows to establish the infectiosity status of these hemodialysis patients. It is therefore very important to evaluate prospectively this diagnosis approach in hemodialysis patients.     

Transformable device that can switch between rigid body and soft body

The materials for transformable robots can roughly be categorized into two types, that is, rigid body and soft body. They have different features, and have merits and demerits, respectively. Robots with rigid body have high stiffness, and are suitable for carrying and holding objects. However, they may injure users if they make contact. Robots with soft body have high flexibility and can make contact safely. However, they have difficulty in retaining particular shapes and are fragile against external force. In this letter, we propose some devices that can switch between rigid body and soft body using phase change of low melting alloy to resolve the problems. We also provide some experimental results with the device to clarify the applicability of the developed devices. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.