Progress Report on NMIJ Acoustic Gas Thermometry at the Triple Point of Water

Herein, progress in the development of an acoustic gas thermometry (AGT) system at the National Metrology Institute of Japan is reported. This AGT system is an initial low-cost version that uses a 1-l quasi-spherical resonator (QSR) made of oxygen-free copper. The system was tested by measuring the speed of sound in argon at the temperature of triple point of water. Measurements were conducted at ten different pressures, ranging from 60 kPa to 420 kPa. The ideal gas limit of the squared speed of sound was obtained through extrapolation, and a preliminary calculation of the Boltzmann constant, which was 12 ppm below the CODATA2014 value, was made. Large inconsistencies among microwave and acoustic modes were observed, which are dominant sources of uncertainty in speed of sound measurements. The system will be improved by replacing the present QSR with another one that is more precisely fabricated.     

Daily oscillation of gene expression associated with nacreous layer formation

Three major organic matrix components, nacrein, MSI60 and N16 have been reported from the nacreous layer of Japanese pearl oyster, Pinctada fucata. Though several in vitro experiments have been carried out to elucidate the functions of these molecules details have not yet been clarified. In this report, we tempt to clarify the gene expression levels encoding the above three proteins between samples of 1) summer and winter seasons and 2) ocean and aquarium environments by using real-time polymerase chain reaction (PCR). It was confirmed that the biomineralization process of P. fucata is mainly influenced by the circatidal rhythm of the ocean environment. The gene expressions coding for N16 and MSI60 increased at the time of high tide, while that of nacrein increased at the time of low tide. The similar tendency observed in N16 and MSI60 showed the possibility that both components are secreted simultaneously, supporting a hypothesis that N16 forms cross-linkage with MSI60 to form the membrane. The expressions of MSI60, N16 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were remarkable in winter season, while no variation was found in the expression level of the nacrein gene in summer and winter season. The study is the first attempt regarding the seasonal and circadian rhythms observed on gene expressions incorporated into molluscan shell formation. The results will give a new insight into the relationship between molluscan physiology and the mechanism of shell formation.     

Photocatalytic activity of transparent porous glass supported TiO2

A porous glass tube with a composition of 96SiO₂·4B₂O₃ (wt%) supported TiO₂ shows high photooxidation activity due to its transparency and large surface area. The surface area of the porous glass tube supported TiO₂ is 10,000 times larger than that of conventional materials. TiO₂ crystals supported are anatase type. Transparency of the porous glass tube is very important. Herein, sol–gel and chemical vapor deposition (CVD) processes were employed as TiO₂ supporting processes. CVD process is more effective. For instance, an aqueous methylene blue solution with 1 ppm concentration almost thoroughly decomposes at a contact time of 300 s using porous glass tube supported TiO₂ prepared by CVD process under irradiating with 10 W low-pressure mercury lamp, on the other hand, opaque porous alumina tube supported TiO₂ was only 25%. The smaller the pore size of the porous glass tube, the larger the transparency and the permeation resistance through porous glass tube. Hence, porous glass tube with ca. 40 nm pore diameter is suitable from the standpoint of a practical use.     

Electronic properties of ruthenium sulfide–carbon cluster composite material obtained by calcination of an alternating ruthenium–S–phenylene hybrid copolymer

Calcination of an alternating ruthenium–S–phenylene hybrid copolymer under an argon atmosphere was found to give nano-sized ruthenium sulfide/carbon cluster composite material. ESR spectral examinations of the material revealed that an electron transfer from ruthenium sulfide particles to carbon clusters took place to raise a visible-light responsive oxidation–reduction function with an oxidation site at ruthenium sulfide particles and a reduction site at carbon clusters. The surface of the calcined material was modified with Pt particles, and the reduction ability of the resulting modified material was examined.     

Thermal design of a closed cabinet with a heat exchanger for inner air cooling

This paper describes a thermal design and simulation method of a closed cabinet with a heat exchanger for inner air cooling. In the controller system that we used for this research, the cabinet is equipped to be outdoors, and the cabinet is sealed to prevent the introduction of dust. Because this system dissipated 630 W in total, it suffered from a problem that the inner air temperature of the cabinet was raised over 30 K. Thus, we installed a heat pipe and heat exchanger in the cabinet, and we also changed the air flow path to realize the best performance of heat exchange according to the results from thermal and fluid simulations using a macroscopic model of heat exchanger to reduce the computational load. We found that the inner air temperature rise was reduced below 15 K, and the measured results were in good agreement with the simulation. © 2001 Scripta Technica, Heat Trans Asian Res, 30(4): 267–279, 2001     

反倾层状岩体边坡稳定性的数值分析

 反倾层状岩体边坡的破坏和普通的滑坡不同,其破坏过程和破坏机制尚未十分清晰。弯曲倾倒是其中的一种特殊破坏形式,这种形式的边坡破坏和地质构造有很大的关系,用通常的连续介质理论不能很好地模拟和解析。根据不连续体理论,利用离散元软件UDEC,模拟弯曲倾倒破坏行为,讨论影响边坡稳定性的各种因素,为实际的边坡施工提供参考数据。通过模拟现场的边坡滑移过程,确定合适的分析参数。在此基础上,改变不同的边坡高度、倾角以及岩层的倾角和厚度,总结影响边坡稳定性的几个重要因素的相互关系。模拟结果表明,除了岩层间的力学参数以外,岩体边坡的稳定性还受岩层的厚度、倾角/走向以及人工边坡倾角的影响。这几个因素相互影响,相互制约边坡的稳定性。人工边坡的设计及施工应该对这几个因素综合考虑。     

复杂条件下长大隧道涌水预测 及其对环境影响评价

 隧道涌水不但影响施工进度、施工费用、稳定和安全,也会引起地下水位的下降。由于环保意识的增强,对隧道涌水控制已成为隧道设计、施工和建设的重要部分。考虑降雨补给、真实三维地形、隧道埋深及时空开挖对隧道涌水的影响,利用地理信息系统(GIS)和FLAC3D对日本九州地区新干线筑紫隧道涌水及其对地下水位的影响进行分析。首先利用GIS中的水理分析将所研究的筑紫隧道周围区域划分为若干个小的流域,对每一个小流域利用tank模型进行降雨渗透分析;然后利用数值三维模型对隧道开挖阶段和使用后的涌水及其对地下水位的影响进行时空预测和分析。     

Daily oscillation of gene expression associated with nacreous layer formation

Three major organic matrix components, nacrein, MSI60 and N16 have been reported from the nacreous layer of Japanese pearl oyster, Pinctada fucata. Though several in vitro experiments have been carried out to elucidate the functions of these molecules details have not yet been clarified. In this report, we tempt to clarify the gene expression levels encoding the above three proteins between samples of 1) summer and winter seasons and 2) ocean and aquarium environments by using real-time polymerase chain reaction (PCR).It was confirmed that the biomineralization process of P. fucata is mainly influenced by the circatidal rhythm of the ocean environment. The gene expressions coding for N16 and MSI60 increased at the time of high tide, while that of nacrein increased at the time of low tide. The similar tendency observed in N16 and MSI60 showed the possibility that both components are secreted simultaneously, supporting a hypothesis that N16 forms cross-linkage with MSI60 to form the membrane. The expressions of MSI60, N16 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were remarkable in winter season, while no variation was found in the expression level of the nacrein gene in summer and winter season.The study is the first attempt regarding the seasonal and circadian rhythms observed on gene expressions incorporated into molluscan shell formation. The results will give a new insight into the relationship between molluscan physiology and the mechanism of shell formation.