Low-bending-loss single-mode fibers for fiber-to-the-home

Recent progress on low-bending-loss single-mode optical fibers for fiber-to-the-home (FTTH) is reviewed. Designing and manufacturing for three types of fibers-a step-index-profile fiber, a trench-index-profile fiber, and a holey fiber-are discussed. The trench-index-profile fibers and the holey fibers are confirmed to be candidates for indoor wiring because of their low bending losses, as well as splice losses.     

A non‐repudiable negotiation protocol for security service level agreements

Security service level agreements (SSLAs) provide a systematic way for end users at home or in the office to guarantee sufficient security level when doing business or exchanging sensitive personal or organizational data with an online service. In this paper, we propose an SSLA negotiation protocol that implements non‐repudiation with cryptographic identities and digital signatures and includes features that make it resistant to denial of service attacks. The basic version of the protocol does not rely on the use of a trusted third party, and it can be used for all kinds of simple negotiations. For the negotiation about SSLAs, the protocol provides an option to use an external knowledge base that may help the user in the selection of suitable security measures. We have implemented a prototype of the system, which uses JSON Web Signature for the message exchange and made some performance tests with it. The results show that the computational effort required by the cryptographic operations of the negotiation protocol remains at a reasonable level. Copyright © 2014 John Wiley & Sons, Ltd.     

Performance evaluation of heat exchanger using alternative refrigerant R407C

R22 (HCFC22) has been widely used as the refrigerant in air conditioners. According to the Montreal protocol for ozone layer protection, the total production of HCFCs has been capped since the beginning of 1996. Zeotropic refrigerant mixture R407C and nearly azeotropic refrigerant mixture R410A have been selected as alternatives to R22. We examined refrigerant passages in heat exchangers used in heat pump‐type room air conditioners using zeotropic refrigerant R407C through simulation, and obtained the following conclusions. In an indoor heat exchanger, a counter flow configuration when operating as a condenser has higher temperature efficiency. When an outdoor heat exchanger operates as an evaporator, a configuration that suppresses the temperature glide by partially reducing the refrigerant passage not only produces high efficiency, but also reduces the frost formation on fins. © 2002 Wiley Periodicals, Inc. Heat Trans Asian Res, 31(8): 626–638, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10064     

Effect of Non-Equilibrium Condensation of Moist Air on Flow Field in Ludwieg Tube

The time-dependent behavior of non-equilibrium condensation of moist air through a Ludwieg tube with a diaphragm downstream is investigated by using a computational fluid dynamics work. The two-dimensional, compressible, Navier-Stokes equations, fully coupled with the condensate droplet growth equations, are numerically solved by a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. Baldwin-Lomax turbulence model is employed to close the governing equations. The present computations represent the experimental flows well. The results obtained show that for an initial relative humidity over 40 %, the periodic excursions of the condensation shock occurs in the Ludwieg tube, and the frequency increases with the initial relative humidity. It is also found that total pressure loss due to non-equilibrium condensation in the Ludwieg tube should not be ignored even for a very low initial relative humidity. Furthermore, the variations of condensation properties are also di     

Carbon-coated stainless steel as PEFC bipolar plate material

Stainless steel is quite attractive as bipolar plate material for polymer electrolyte fuel cells (PEFCs). Passive film on stainless steel protects the bulk of it from corrosion. However, passive film is composed of mixed metal oxides and causes a decrease in the interfacial contact resistance (ICR) between the bipolar plate and gas diffusion layer. Low ICR and high corrosion resistance are both required. In order to impart low ICR to stainless steel (SUS304), carbon-coating was prepared by using plasma-assisted chemical vapor deposition. Carbon-coated SUS304 was characterized by Raman spectroscopy and atomic force microscopy. Anodic polarization behavior under PEFC operating conditions (H₂SO₄ solution bubbled with H₂ (anode)/O₂ (cathode) containing 2 ppm HF at 80 °C) was examined. Based on the results of the ICR evaluated before and after anodic polarization, the potential for using carbon-coated SUS304 as bipolar plate material for PEFC was discussed.     

Study on the compressible viscous flows through a straight pipe

When sonic nozzles of significantly smaller diameter are used as standard flow meters, the critical backpressure ratio is affected by the boundary layer at the nozzle throat. It is known that, as the flow pathway is complicated in actual valves, the critical pressure ratio differs from the ideal value. However, the effect of the boundary layer thickness on choking criteria is still controversial. Choking phenomenon in a sonic nozzle fitted with a straight circular pipe of variable length is investigated numerically and the results are compared with experimental and theoretical ones. The results show that the actual critical pressure ratio is less than the ideal value and it decreases with increase in pipe length. The effect of boundary layer thickness on main flow Mach number is also made clear in this work. In addition, sonic conductance and pressure loss in actual viscous flows computed are compared with the ISO 6358 standard.     

Complex Hydrides for Electrochemical Energy Storage

Complex hydrides have energy storage‐related functions such as i) solid‐state hydrogen storage, ii) electrochemical Li storage, and iii) fast Li‐ and Na‐ionic conductions. Here, recent progress on the development of fast Li‐ionic conductors based on the complex hydrides is reported. The validity of using them as electrolytes in all‐solid‐state lithium rechargeable batteries is also examined. Not only coated oxides but also bare sulfides are found to be applicable as positive electrode active materials. Results related to fast Na‐ionic conductivity in the complex hydrides are presented. In the last section, the future prospects for battery assemblies with high‐energy densities, and Mg ion batteries with the liquid and the solid‐state electrolytes are discussed.     

Chitosan-gelatin/hydroxyapatite-based scaffold associated with mesenchymal stem cells differentiate into osteoblasts improves the surface of the bone lesion in mice C57BL/6J

Extensive injuries to bone tissue are still considered a significant clinical challenge; therefore, developing new bone tissue engineering (BTE) strategies is still necessary. This work aims to construct and characterize a chitosan-gelatin/hydroxyapatite-based (CG/H) scaffold to provide well-design support for mesenchymal stem cell (MSC) growth and differentiation to osteoblasts. First, the CG/H scaffolds are construct by freeze-drying. Then, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, x-ray diffraction, water uptake, and degradation profiles evaluate the material's surface. In addition, the CG/H morphological, biochemical, and MSC adhesion processes and growth behavior are also assess, indicating reasonable adhesion rates to the surface, low material cytotoxicity, and excellent alkaline phosphatase activity compared to control on the cellular framework. Based on these results, we obtain a highly biocompatible scaffold and that can support osteoblast differentiation. Finally, the in vivo studies demonstrate the CG/H scaffold with MSC adhere is capable of differentiating into osteoblasts, and the application of this scaffold is able to significantly enhance the closure of the bone lesion. Therefore, the CG/H scaffold has potential clinical application for bone regeneration.     

CCL4 Regulates Eosinophil Activation in Eosinophilic Airway Inflammation

Eosinophilic chronic rhinosinusitis (ECRS) is a refractory airway disease accompanied by eosinophilic inflammation, the mechanisms of which are unknown. We recently found that CCL4/MIP-1β—a specific ligand for CCR5 receptors—was implicated in eosinophil recruitment into the inflammatory site and was substantially released from activated eosinophils. Moreover, it was found in nasal polyps from patients with ECRS, primarily in epithelial cells. In the present study, the role of epithelial cell-derived CCL4 in eosinophil activation was investigated. First, CCL4 expression in nasal polyps from patients with ECRS as well as its role of CCL4 in eosinophilic airway inflammation were investigated in an in vivo model. Furthermore, the role of CCL4 in CD69 expression—a marker of activated eosinophils—as well as the signaling pathways involved in CCL4-mediated eosinophil activation were investigated. Notably, CCL4 expression, but not CCL5, CCL11, or CCL26, was found to be significantly increased in nasal polyps from patients with ECRS associated with eosinophil infiltration as well as in BEAS-2B cells co-incubated with eosinophils. In an OVA-induced allergic mouse model, CCL4 increased eosinophil accumulation in the nasal mucosa and the bronchoalveolar lavage (BALF). Moreover, we found that CD69 expression was upregulated in CCL4-stimulated eosinophils; similarly, phosphorylation of several kinases, including platelet-derived growth factor receptor (PDGFR)β, SRC kinase family (Lck, Src, and Yes), and extracellular signal-regulated kinase (ERK), was upregulated. Further, CCR5, PDGFRβ, and/or Src kinase inhibition partially restored CCL4-induced CD69 upregulation. Thus, CCL4, which is derived from airway epithelial cells, plays a role in the accumulation and activation of eosinophils at inflammatory sites. These findings may provide a novel therapeutic target for eosinophilic airway inflammation, such as ECRS.     

A computational investigation on the control of cavity-induced pressure oscillations using sub-cavity

A computational investigation has been conducted to determine the effectiveness of a passive control technique ofattenuating cavity-induced pressure oscillations in a confined two-dimensional supersonic flow.The passivecontrol technique is achieved by fitting two flat plates near the front wall of a square cavity at Mach number 1.83at the cavity entrance.The results showed that the flat plates attached near the front wall of the cavity,discouraged the formation of feedback loop which is widely believed to be the reason of cavity resonance.Theresultant amount of attenuation of pressure oscillations was also dependent on the length of the fiat plate used asan oscillation suppressor.