Power extraction using flow-induced vibration of a circular cylinder placed near another fixed cylinder

We conducted an experiment in a towing tank to investigate the performance of an energy extraction system using the flow-induced vibration of a circular cylinder. This experiment tested three different cases involving the following arrangements of cylinder(s) of identical diameter: the upstream fixed–downstream movable arrangement (case F); the upstream movable–downstream fixed arrangement (case R); and a movable isolated cylinder (case I). In cases F and R, the separation distance (ratio of the distance between the centers of the two cylinders to their diameters) is fixed at 1.30. Measurement results show that while cases F and I generate vortex-induced vibration (VIV) resonance responses, case R yields wake-induced vibration (WIV) at reduced velocity over 9.0, which is significantly larger than that of the VIV response, leading to the induction of higher electronic power in a generator. Accordingly, primary energy conversion efficiency is higher in the case involving WIV.     

Comparative investigation of Au nano-particle formation process dependent upon various protective agents

Formation process of gold nanoparticles was investigated by near-field heterodyne transient grating method. In the absence of the protective agents, although the diffusion of H[Au^ICl₂] could be observed after the photo-reduction of H[Au^IIICl₄], the diffusion of nanoparticle-seeds was not observed. On the other hand, in the presence of the protective agents, the diffusion of a complex molecule (Au and protective agent) and nanoparticle-seeds could be observed. From these results, it was found that enough amount of the complex is essential for the nanoparticle formation. We also investigated the formation process with four different chemicals as a protective agent. The hydrodynamic radius of nanoparticle-seeds generated in the poly(vinyl pyrrolidone) and TritonX-100 solutions were larger than those generated in the Tween 20 and Brij 58 solutions. The former two have hydrophilic chain in the molecular structure; on the other hand, the latter two have hydrophobic alkyl chain. Based on those facts, we concluded that the interaction between the chains of the complex molecule plays an important role in the nanoparticle formation process.     

Pyrolysis of amines: Infrared spectrum of methyleneimine

Methyleneimine was detected in the gas phase by a moderately high resolution infrared spectrometer as one of the intermediate species produced by a pyrolysis of amines. Observed vibrational frequencies of some isotopic derivatives have been combined with the ab initio values to reach a most reliable force constants set. Some other spectroscopic parameters, involving geometrical parameters and dipole moment derivatives, have also been calculated ab initio and compared with the observation. Its half-life in our experimental apparatus was about 10 min, which is much longer than the previously reported values, 0.1 or 10 sec.     

Optical interconnection between different spatial modes using double phase conjugate mirror with polarization alignment system

We propose a fundamental interconnection method using a polarization alignment system for waveguides having different spatial modes. In addition, as an example for the verification of the fundamental operation, we demonstrate an interconnection between a photonic crystal fiber and a laser that have obviously different spatial modes. The polarization alignment system operates synergistically with a self-written waveguide formed with a double phaseconjugate mirror. This technique enables us to interconnect a photonic crystal fiber with a laser source without complicated and time-consuming optical alignment. In this method, although it is not necessary to perform an external control for interconnection, the waveguide most suitable for connection is formed autonomously in a Sn₂P₂S₆:Sb crystal developed for this purpose. There was a marked reduction in the polarization dependence of coupling efficiency, compared with that observed using a stand-alone double phase-conjugate mirror.     

An MRA study of vascular stenosis in a pig model using CH3-DTPA-Gd (NMS60) and Gd-DTPA

PURPOSE: This study used an experimental arterial stenosis model in pigs to evaluate the utility of a new medium-weight MRI contrast agent, NMS60 (a synthetic oligomeric Gd complex containing three Gd(3+) atoms, molecular weight of 2158 Da) compared to Gd-DTPA for contrast-enhanced MRA. MATERIALS AND METHODS: We used six male white hybrid pigs. Under anesthesia, one femoral artery was exposed and an inflatable cuff placed around it. The cuff was tightened around the vessel until 80-90% stenosis was achieved using digital subtraction angiography as a guide. Animals were then immediately transferred to the MRI scanner and images acquired pre- and postcontrast injection (0.1 or 0.2 mmol Gd/kg Gd-DTPA or NMS60, as a rapid bolus) using high-resolution and dynamic MRA. RESULTS: The dynamic MRA scans acquired during contrast bolus injection clearly showed the stenosed femoral artery as a segment of close to zero enhancement during the arterial phase of the bolus transit, while on the high-resolution scans the stenosis was difficult to detect due to venous signal contamination. The signal-to-noise at peak enhancement on the dynamic scans was significantly greater with 0.1 mmol Gd/kg NMS60 compared to 0.1 mmol Gd/kg Gd-DTPA (14.6 vs. 9.9, P < .05) and not significantly greater than 0.2 mmol Gd/kg (14.6 vs. 12.8). DISCUSSION AND CONCLUSION: This new medium-weight contrast agent demonstrated significantly greater enhancement than Gd-DTPA and may be valuable to aid detection of vascular stenosis in humans.     

Surface treatment of CaCO3 with a mixture of amino- and mercapto-functional silane coupling agents and tensile properties of the rubber composites

In order to reinforce the composite consisting of isoprene rubber (IR) and calcium carbonate (CaCO₃) particles, the surface treatment of CaCO₃ particles with a mixture of amino- and mercapto-functional silane coupling agents was investigated. The quantity of chemisorbed silanes in treated CaCO₃ measured using thermogravimetry was greater for amino- than for mercapto-silane and for the tri- than for the dialkoxy structure. Second, the molecular mobility of polycondensate of the mixtures with the trialkoxy structure measured using ¹H pulse nuclear magnetic resonance had the least molecular mobility, i.e., formed the highest density network. The greater values of stress at 500% strain, fracture stress, and elongation at break were determined for the treatment with amino- and mercapto-functional silanes having a trialkoxy structure from the stress-strain curves of composite. The mixture treatment with dialkoxy structure and with amino- or mercapto-functional silane only did not improve the mechanical properties sufficiently. Interactions between the amino group and the CaCO₃ surface, covalent bonding between the mercapto group and the IR, and high density network formation of trialkoxy silane were important for improving the mechanical properties of the composite.     

Baryogenesis in false vacuum

The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators.