Analysis of electromagnetic waveguide bends by three-dimensional finite element method with edge elements

An approach based on the finite element method (FEM) with the rectangular-parallelepipd edge element is proposed for the analysis of electromagnetic waveguide bends. Here, to be permissible for analysis of various electromagnetic waveguides, the analytical relations in the uniform waveguide are constructed numerically by using the FEM with the rectangular edge element. To confirm the validity and versatility of this approach, bends of a hollow waveguide, a half-filled dielectric waveguide, and a finline are analyzed. © 1996 John Wiley & Sons, Inc.     

Pannexin 1-Mediated ATP Signaling in the Trigeminal Spinal Subnucleus Caudalis Is Involved in Tongue Cancer Pain

Pain is one of the most severe concerns in tongue cancer patients. However, the underlying mechanisms of tongue cancer pain are not fully understood. We investigated the molecular mechanisms of tongue cancer-induced mechanical allodynia in the tongue by squamous cell carcinoma (SCC) inoculation in rats. The head-withdrawal threshold of mechanical stimulation (MHWT) to the tongue was reduced following SCC inoculation, which was inhibited by intracisternal administration of 10Panx, an inhibitory peptide for pannexin 1 (PANX1) channels. Immunohistochemical analyses revealed that the expression of PANX1 was upregulated in the trigeminal spinal subnucleus caudalis (Vc) following SCC inoculation. The majority of PANX1 immunofluorescence was merged with ionized calcium-binding adapter molecule 1 (Iba1) fluorescence and a part of it was merged with glial fibrillary acidic protein (GFAP) fluorescence. Spike frequencies of Vc nociceptive neurons to noxious mechanical stimulation were significantly enhanced in SCC-inoculated rats, which was suppressed by intracisternal 10Panx administration. Phosphorylated extracellular signal-regulated kinase (pERK)-immunoreactive (IR) neurons increased significantly in the Vc after SCC inoculation, which was inhibited by intracisternal 10Panx administration. SCC inoculation-induced MHWT reduction and increased pERK-IR Vc neuron numbers were inhibited by P2X7 purinoceptor (P2X7R) antagonism. Conversely, these effects were observed in the presence of P2X7R agonist in SCC-inoculated rats with PANX1 inhibition. SCC inoculation-induced MHWT reduction was significantly recovered by intracisternal interleukin-1 receptor antagonist administration. These observations suggest that SCC inoculation causes PANX1 upregulation in Vc microglia and adenosine triphosphate released through PANX1 sensitizes nociceptive neurons in the Vc, resulting in tongue cancer pain.     

Case Study: Hydraulic Modeling of Runoff Processes in Ghanaian Inland Valleys

The inland valleys of West Africa are strategic in terms of food security and poverty alleviation, but scientific studies on hydrologic processes happening in these environments have not been well documented. Modeling approaches presented in this paper are an attempt to better comprehend hydraulic phenomena occurring in inland valleys. An inland valley situated in the Northern Region of Ghana is set as the study site. The inland valley comprises well-drained uplands and hydromorphic valley bottoms. There are several earthen dams across the valley bottoms, which are at the same time seasonal wetlands cultivated to rice during the rainy season. A finite volume model for the shallow water equations is developed to numerically simulate surface runoff flows in the valley bottoms during flood events. Innovation is necessitated to handle a series of different hydraulic phenomena. Flux-splitting and data reconstruction techniques are used to achieve stable computation in the complex topography of the valley bottoms. Standard problems of oblique hydraulic jump and dam break flows are used to test the accuracy of the numerical model. The Manning’s roughness coefficient is determined from calibration in another Ghanaian watershed located in the Eastern Region. Using actually observed time series data of rainfall intensity, surface flows during the rainfall events are simulated in the computational domain representing the valley bottoms of the study area. Observed data of water levels in the dams are compared to predictions, and discrepancies between them are examined from the hydrological point of view. In the case of a hypothetical flood event, cascading collapses of the dams and flooding of cultivated fields are reproduced.     

Characterization of porous silicon nitride ceramics using bentonite as binder and sintering additive

The effect of bentonite addition on extrusion behavior, open porosity, microstructure, and mechanical properties was investigated. The results showed that paste with an appropriate amount of bentonite had a good extrusion behavior. The resultant microstructures consisted of rod-like silicon nitride grains and some intergranular amorphous phase. Furthermore, superior mechanical properties were obtained. Using cheap but effective bentonite as inorganic binder as well as sintering aid is a promising eco-friendly preparation route for cost-effective porous silicon nitride ceramics.     

A Thin Carbon‐Fiber Web as a Scaffold for Bone‐Tissue Regeneration

Due to the rapid progress being made in tissue regeneration therapy, biomaterials used as scaffolds are expected to play an important role in future clinical application. We report the development of a 3D web (sheet) consisting of high‐purity carbon fibers in a nanoscale structure. When the thin carbon‐fiber web (TCFW) and recombinant human bone morphogenetic protein 2 (rhBMP‐2) composite is implanted in the murine back muscle, new ectopic bone is formed, and the values of the bone mineral content and bone mineral density are significantly higher than those obtained with a collagen sheet. Observation of the interface between the carbon fibers and bone matrix reveal that the fibers are directly integrated into the bone matrix, indicating high bone‐tissue compatibility. Further, the rhBMP‐2/TCFW composite repairs a critical‐size bone defect within a short time period. These results suggest that the TCFW functions as an effective scaffold material and will play an important role in tissue regeneration in the future.     

Fabrication and efficient photocatalytic degradation of methylene blue over CuO/BiVO4 composite under visible-light irradiation

CuO/BiVO₄ composite photocatalysts were prepared by solution combustion synthesis method and impregnation technique. X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scan electron microscopy and UV-vis diffusion reflectance spectra were used to identify the physical properties and photophysical properties of CuO/BiVO₄ composite photocatalysts. The photocatalysts exhibit the enhanced photocatalytic properties for degradation of methylene blue under visible-light (λ > 420 nm). The mechanism of improved photocatalytic activity is also discussed.     

Characterization of Tin-catalyzed silicon nanowires synthesized by the hydrogen radical-assisted deposition method

Tin-catalyzed silicon nanowires (SiNWs) were synthesized at various hydrogen gas flow rates using the hydrogen radical-assisted deposition method. Large quantities of SiNWs with various crystal phases were synthesized and their characteristics were estimated. Tin-capped SiNWs were straightly grown and their structures were changed with increasing hydrogen gas flow rates. Their diameters on the bottom side were increased ranging from approximately 50 to 200 nm and their lengths extended up to ~ 2 µm with increasing hydrogen gas flow rates.     

长白山红蚂蚁在体外肿瘤细胞增殖抑制作用研究

对长白山红蚂蚁(Forimica aquilonia)的抗肿瘤进行活性研究。MTT 比色法测定长白山红蚂蚁提取物对大鼠肝癌细胞dRLh84 增殖抑制作用,荧光显微镜观察提取物作用于dRLh84 细胞后的肿瘤细胞的细胞核变化。结果表明：长白山红蚂蚁乙酸乙酯提取物具有抑制dRLh84 细胞增殖作用,且呈剂量- 效应关系。乙酸乙酯提物以乙酸乙酯和水进行液液萃取后,活性成分移动至乙酸乙酯相,证明活性物质为极性较小的物质。荧光显微镜观察结果表明,长白山红蚂蚁乙酸乙酯提取物能引起dRLh84 细胞凋亡。     

Oxygen ion conductivity of the ceria-samarium oxide system with fluorite structure

Ionic conduction of oxygen in the ceria-samarium oxide system was investigated as a function of temperature, partial pressure of oxygen and the oxide composition, together with its crystal structure, density and defect structure. The ionic conductivity of (CeO₂)_1–x(SmO_1.5)_x was the highest in ZrO₂-, ThO₂- and CeO₂-based oxide systems. The system CeO₂-SmO_1.5 consisted of the solid solution with a fluorite structure atx<50 at.%. The ionic transference number was nearly unity between 600 and 900°C. With an increase in Sm₂O₃ content, the ionic conductivity gradually decreased due to a decrease in mobility of oxygen ions. The samarium oxide-doped ceria was less reducible than pure and alkaline earth oxide-doped ceria.     

Effects of Anode Microstructure on Mechanical and Electrochemical Properties for Anode‐Supported Microtubular Solid Oxide Fuel Cells

The effects of anode microstructure on mechanical and electrochemical properties were investigated for anode‐supported microtubular solid oxide fuel cells (SOFCs). The anode microstructures can be varied by the change in pore formers. For example, the acrylic resin pore former was burnt more rapidly at lower temperature than the graphite pore former during sintering. The acrylic resin pore former can introduce macropores with a diameter of several micrometers in nickel–yttria‐stabilized zirconia (Ni–YSZ) anode. The walls of the macropores were packed with the nickel and YSZ particles. Although the Ni–YSZ anode microtube using the 10 wt% acrylic resin pore former was compatible with high porosity and mechanical strength, the maximum fuel utilization was limited to 72%. On the other hand, the graphite pore former can produce a relatively uniform distribution of micropores with a diameter of several hundred nanometers. The mechanical strength was reduced with a rise in porosity for the Ni–YSZ microtube using the graphite pore former in comparison with the acrylic resin. However, a high fuel utilization of 93% was realized for the microtubular SOFCs using the 10 wt% graphite pore former in spite of lower porosity than the acrylic resin. The selection of a pore former is important to obtain higher power generation efficiency for anode‐supported microtubular SOFCs.