Effect of cavities inside tube banks on acoustic resonance

In the present paper the attention is focused on the effect of small cavities inside in-line tube banks on acoustic resonance which occurred in the two-dimensional model of boiler. We measured the sound pressure level, the amplitude and the phase delay of acoustic pressures and the gap velocity. As a result, we found many peak frequencies of sound pressure level with different Strouhal numbers, mainly about S1=0.15, 0.26 and 0.52. The variation of SPL for S,=0.26, 0.52 components in the tube banks with cavities was the same as the result of no cavities. The existence of cavities inside in-line tube banks caused the resonance of St=0.15. And the acoustic resonance of the first mode in the transverse direction was generated if the small cavities existed inside the tube banks. This resonance was not generated from the tube banks of no cavities. The resonance onset velocity in the transverse mode was fairly slower than that of no cavities. It was easy to generate acoustic resonance when there were small cavities inside in-line tube banks.     

豆酱(日本味噌)含盐量对胃癌及血压的影响

豆酱(日本味噌)是人们喜欢食用的发酵食品,但其所含食盐量较高(日本豆酱含盐量10%～13%),而盐分过量摄入被认为是胃癌、高血压等生活方式疾病的致病因子。日本的免疫学调查表明经常喝酱汤的人,癌症发病率低,为此,笔者做了动物试验,研究了在饵料中,分别以豆酱形式添加食盐与以食盐的形式直接添加对癌症、高血压的影响,以及添加不同发酵时间的豆酱对胃癌的抑制效果。试验结果表明:在盐分含量相同的情况下,以豆酱形式添加食盐的饵料不仅不会增加胃癌的发病率,相反能抑制胃癌的发生,而且随着豆酱发酵时间的延长,对胃癌的抑制效果越强;另外也不会引起血压升高。因此,建议将以豆酱为原料制作的酱汤做为健康食品进行推广。     

Improved preservation of fine structure of deep-sea microorganisms by freeze-substitution after glutaraldehyde fixation

A method was proposed for improving preservation of ultrastructures of deep-sea microorganisms by using rapid-freeze freeze-substitution after glutaraldehyde fixation. This method produced clear high-resolution images of cells appearing in their natural state, close to the quality of images obtained by rapidly freezing freeze-substituted specimens of living cells. The method may be useful for observing any microorganism when rapid freezing of living samples is difficult and only glutaraldehyde fixation can be carried out.     

Ionomer content in the catalyst layer of polymer electrolyte membrane fuel cell (PEMFC): Effects on diffusion and performance

The percolating paths of the carbons and electrolytes in a cathode catalyst layer (CCL) could be successfully visualized in three-dimensions in order to investigate both the electronic and ionic connectivity by modeling a three-dimensional (3-D), meso-scale CCL of a polymer electrolyte membrane fuel cell (PEMFC). The effective Knudsen diffusion coefficients could also be obtained by computing pore tortuosity values. Electrochemical simulation studies were carried out by feeding air at 70 °C. Low platinum (Pt) loading (0.1 mg cm⁻²) catalysts with ionomer contents ranging from 14 to 50% were studied. The performance of a PEMFC electrode was affected by the ionomer content which is optimal at about 33%. In this case, both electronic and ionic connectivity produced the broadest active surface area of the Pt catalyst. The polarization drop tendency was in good agreement with the experiment, and this percolation study could successfully explain the existence of an optimum amount of ionomer.     

Real-Time Reactions in Supervisory Control According to Data Freshness

Supervisory control systems in plants mustacquire data without any loss and react for state changes. Someof state change should be reacted in a real-time manner, whileothers may be notified in a best-effort manner. To implementa middleware which works as a server in supervisory control systemsin an acceptable cost, we value the data freshness which meanshow much time has passed from the occurrence of the data. Inthis paper, we present the Active Ring model whichincorporates the ECA mechanism into circular areas. With rulesusing only the latest data, the ECA mechanism realizes time-criticalreactions as firm real-time tasks. In addition to that, the rulestrigger best-effort notification which is realized as a softreal-time task. The middleware works in numerous plants for steelmill, water purifying, and tunnel ventilation. This paper includesan experimental result revealing that the ActiveRing model is effective to provide service according to the datafreshness.     

Dependence of polymer electrolyte fuel cell performance on preparation conditions of slurry for catalyst layers

The catalyst slurry used to form the catalyst layer of a polymer electrolyte fuel cell (PEFC) must be mixed for a sufficiently long period for good and stable cell performance. However, the optimum mixing duration must be determined from the viewpoint of process design. We prepared slurries with various amounts of Nafion and examined the influence of the slurry mixing time on the viscosity of the slurry, the size of the pores and distribution of elements in the catalyst layer, and the cell voltage of the PEFC. We found that when the Nafion content is optimum, these properties change gradually and stabilize after a sufficiently long mixing time as the progression of the adsorption of Nafion to catalyst particles. However, when the Nafion is comparatively low, although the properties stabilize after sufficient mixing, the Nafion molecules are first dispersed and then localized around aggregates. This reduces cell performance when mixing excessively long. These differences in the structural and electrochemical behaviors could be predicted by measuring the variation in viscosity during the mixing process.     

Mesoscopic architectures of porous coordination polymers fabricated by pseudomorphic replication

The spatial organization of porous coordination polymer (PCP) crystals into higher-order structures is critical for their integration into separation systems, heterogeneous catalysts, ion/electron transport and photonic devices. Here, we demonstrate a rapid method to spatially control the nucleation site, leading to the formation of mesoscopic architecture made of PCPs, in both two and three dimensions. Inspired by geological processes, this method relies on the morphological replacement of a shaped sacrificial metal oxide used both as a metal source and as an 'architecture-directing agent' by an analogous PCP architecture. Spatiotemporal harmonization of the metal oxide dissolution and the PCP crystallization allowed the preservation of very fine mineral morphological details of periodic alumina inverse opal structures. The replication of randomly structured alumina aerogels resulted in a PCP architecture with hierarchical porosity in which the hydrophobic micropores of the PCP and the mesopores/macropores inherited from the parent aerogels synergistically enhanced the material's selectivity and mass transfer for water/ethanol separation.