•A sphere is launched vertically upward in water toward the calm free surface.•Investigation the effects of the submergence depth on the interfacial water sheet.•Energy distribution reached ...equilibrium at deeper water depths.•The interfacial water sheet is self-similar at the equilibrium region of energy.•Findings will contribute the modeling of the water exit problem.
The water exit problem is a fundamental problem in fluid dynamics, and the behavior of the air–water interface and the energy transition of an object exiting water have not been thoroughly investigated. In this study, a solid sphere with a density of 2.64×103kg/m3 and diameter of d=25.4 mm was launched vertically upward in water toward the air–water interface. The motion of the sphere and the behavior of the interface were investigated for varying submergence depths H from the launch position of the sphere to the interface. The launch velocity was set so that the Reynolds number immediately after the sphere passed the air–water interface was about 3000 for all cases of H. The kinetic and potential energies of the sphere and the energy lost because of the air–water interface (i.e., interfacial containing energy) were estimated based on the classical law of energy conservation. For H/d⩽3, the ratio between the kinetic energy immediately after passing through the air–water interface and the potential energy at the maximum displacement position decreases with increasing H, but this energy ratio takes a constant value of 0.57 for H/d⩾4. Additionally, for H/d⩾4, kinetic energy is transformed to potential energy and interfacial containing energy at a fixed ratio for each vertical position. The spreading characteristics of the water mass after the sphere has passed the air–water interface and the thickness and width of the interfacial water sheet when the top of the sphere reached the calm free surface were investigated by focusing on their relationship to the energy distribution. For H/d⩾4, where the energy ratio takes a constant value, the increase in the rate of spread of the water mass with increasing H/d is clearly smaller than that of H/d⩽4. Furthermore, for H/d⩾4, the ratio between the thickness and width of the interfacial water sheet is constant. In other words, in the region where the ratio between the kinetic energy of the sphere immediately after passing through the air–water interface and the potential energy at the maximum displacement position has a constant value, the shape of the interfacial water sheet is self-similar. These findings contribute to the determination of variable parameters when modeling the water exit problem.
A spherical particle with a diameter of 25.4 mm and density of 2640 kg/m3 was launched vertically upward toward the free surface of calm water. The Froude number of the particle passing through the ...water surface was varied. The dependence of the Froude number on the particle motion and water surface behavior was investigated from the instant the particle crossed the water surface until it attained its maximum displacement position. Based on the classical energy conservation law, the energy lost in the interaction between the particle and water surface (i.e., interface containing energy, Eo) was estimated. Eo was found to increase with the increase in the Froude number when the particle crossed the water surface. In addition, owing to Eo at the maximum displacement position of the spherical particle, the height and width of the interfacial water sheet changed by the same ratio at the point of intersection of the upper side of the particle with the calm water surface. This result was in agreement with that obtained by changing the submergence depth, as reported by Takamure and Uchiyama (2020). This finding suggests that the characteristics of the interfacial water sheet are the dominant parameters influencing the interface containing energy. The presented findings can help determine the parameters to model the water exit problem.
•A spherical particle is launched vertically upward in water.•Investigation of the Froude number effect on the water surface behavior.•Interfacial water sheets have a self-similar property.•The thickness and width of the interfacial water sheet are the dominant parameters.•The present findings can help determine the parameters to model the water exit problem.
To investigate the dynamics of a sphere's motion and the behavior of the air–water interface induced by the sphere, a solid sphere is launched vertically upward in water toward the air–water ...interface. Four spheres with different densities ρp were studied: Sphere A (ρp = 7930kg/m3), Sphere B (ρp = 3900kg/m3), Sphere C (ρp = 2180kg/m3), and Sphere D (ρp = 1360kg/m3). By experimentally visualizing the sphere motion in water, their launch velocity can be set with high accuracy. When a sphere passes through the air–water interface, it makes the interface more complex and entrains water. Additionally, spheres with a small value of ρp were demonstrated to not always vertically collide with the air–water interface; as a result, different behaviors of spheres can be observed in the air.
•A solid sphere is launched vertically upward in water toward the air–water interface.•Investigation the dynamics of a sphere's motion and the behavior of the air–water interface induced by the sphere.•Four spheres with different densities were studied for comparison.•When a sphere passes through the air–water interface, it makes the interface more complex and entrains water.•Spheres with a small density were demonstrated to not always vertically collide with the air–water interface. Display omitted
Matrix metalloproteinases (MMPs) bound to dentin contribute to the progressive degradation of collagen fibrils in hybrid layers created by dentin adhesives. This study evaluated the MMP-inhibiting ...potential of quaternary ammonium methacrylates (QAMs), with soluble rhMMP-9 and a matrix-bound endogenous MMP model. Six different QAMs were initially screened by a rhMMP-9 colorimetric assay. For the matrix-bound endogenous MMPs, we aged demineralized dentin beams for 30 days in calcium- and zinc-containing media (CM; control), chlorhexidine, or QAMs in CM to determine the changes in dry mass loss and solubilization of collagen peptides against baseline levels. The inhibitory effects of QAMs on soluble rhMMP-9 varied between 34 and 100%. Beams incubated in CM showed a 29% decrease in dry mass (p < 0.05), whereas beams incubated with QAMs showed only 0.2%-6% loss of dry mass. Significantly more solubilized collagen was detected from beams incubated in CM (p < 0.05). It is concluded that QAMs exhibited dentin MMP inhibition comparable with that of chlorhexidine, but required higher concentrations.
In this study, experiments and numerical simulations are performed where a hollow particle with a uniaxial through–hole is dropped freely in water, and its behavior is investigated. The distribution ...of falling particle trajectories reveals significant deviation in the direction perpendicular to the through–hole of the particle. In addition, the pressure distribution at the particle surface and the vorticity field of the wake of the particle are distributed asymmetrically in the plane perpendicular to the through–hole of the particle. Conversely, this pressure distribution and vorticity field are distributed symmetrically with respect to the direction parallel to the through–hole of the particle. Thus, this study clarifies that the movement of the particle in the direction parallel to the through–hole is suppressed. These results provide valuable novel insights into the control of particle motion.
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•Falling study of a spherical particle with a uniaxial through-hole.•Investigation of the trajectory distribution of a falling particle.•The falling behavior is different in the direction perpendicular to the through-hole.•The vorticity maintains symmetry under the influence of a through-hole.•The particle motion in the direction parallel to the through-hole is suppressed.
In order to further improve noise performance and achieve higher sensitivity, we have investigated a highly sensitive MI element by controlling anisotropy, and have analyzed noise components of a MI ...sensor by using a femto-tesla MI sensor system with a synchronized peak-to-peak detector. According to the results, sensitivity of a MI element decreases when tension increases. Meanwhile, sensitivity of a MI element is also linearly proportional to the ratio of impedance change and anisotropy field (∆Z/Hk). The theoretical model shows the same effect as measurement results. Furthermore, the noise of a MI sensor is considered to be mainly due to circuit noise, fluctuation of wire magnetic moment (thermal magnetic noise), and irreversible movement of a domain wall trapped by impurities and scratches on a wire surface (Barkhausen noise). The lowest thermal magnetic noise of amorphous wire calculated in our study is approximately 60 fT. Meanwhile, thermal magnetic noise and magnetic noise due to irreversible movement of a domain wall have been demonstrated as a function of the magnetic anisotropy.
We have investigated the effect of N2 fraction Formula Omitted in Ar–N2 sputtering gas on the tunneling magnetodielectric (TMD) effect in Co–(Si–N) nanogranular films. Co–(Si–N) films were deposited ...by co-sputtering Co and Si3N4 targets in Ar-Formula Omitted vol.%N2 mixture gas with different N2 gas fractions Formula Omitted of 0–30. All deposited films had a nanogranular structure composed of Co nanogranules with a diameter of 1–3 nm embedded in a Si–N matrix. We realized the TMD effect in the films for Formula Omitted, and the film deposited in Ar-6.6 vol.%N2 gas showed the highest dielectric variations in a magnetic field. For Formula Omitted, TMD peak frequency Formula Omitted decreased from 17 to 40 kHz with increasing Formula Omitted because of the increase in intergranular spacing Formula Omitted. On the other hand, for Formula Omitted, Formula Omitted increased from 40 kHz to 3.3 MHz as Formula Omitted increased since both Formula Omitted in the out-of-plane direction and Formula Omitted, which indirectly represents the measure of the distribution of Formula Omitted, decreased. This study provides a new way to tailor the frequency response of the TMD effect.
The release of radioactive isotopes (mainly 137Cs, 134Cs and 131I) from the crippled Fukushima Daiichi Nuclear Plant remains a serious problem in Japan. To help identify radiation hotspots and ensure ...effective decontamination operation, we are developing a novel Compton camera weighting only 1kg and measuring just ∼10cm2 in size. Despite its compactness, the camera realizes a wide 180° field of vision with a sensitivity about 50 times superior to other cameras being tested in Fukushima. We expect that a hotspot producing a 5μSv/h dose at a distance of 3m can be imaged every 10s, with angular resolution better than 10° (FWHM). The 3D position-sensitive scintillators and thin monolithic MPPC arrays are the key technologies developed here. By measuring the pulse-height ratio of MPPC-arrays coupled at both ends of a Ce:GAGG scintillator block, the depth of interaction (DOI) is obtained for incident gamma rays as well as the usual 2D positions, with accuracy better than 2mm. By using two identical 10mm cubic Ce:GAGG scintillators as a scatterer and an absorber, we confirmed that the 3D configuration works well as a high-resolution gamma camera, and also works as spectrometer achieving typical energy resolution of 9.8% (FWHM) for 662keV gamma rays. We present the current status of the prototype camera (weighting 1.5kg and measuring 8.5×14×16cm3 in size) being fabricated by Hamamatsu Photonics K.K. Although the camera still operates in non-DOI mode, angular resolution as high as 14° (FWHM) was achieved with an integration time of 30s for the assumed hotspot described above.
•We are developing a novel Compton camera weighting only 1kg and measuring just ∼10×10cm2 in size.•The camera realizes a wide 180°field of vision with a sensitivity about 50 times superior to other cameras being tested in Fukushima.•The depth of interaction (DOI) is obtained for incident gamma rays as well as the usual 2D positions.•We present the current status of the prototype camera (weighting ∼1.5kg and measuring 8.5×14×16cm3 in size) being fabricated by Hamamatsu Photonics K.K.
Recent awareness that most microorganisms in the environment are resistant to cultivation has prompted scientists to directly clone useful genes from environmental metagenomes. Two screening methods ...are currently available for the metagenome approach, namely, nucleotide sequence-based screening and enzyme activity-based screening. Here we have introduced and optimized a third option for the isolation of novel catabolic operons, that is, substrate-induced gene expression screening (SIGEX). This method is based on the knowledge that catabolic-gene expression is generally induced by relevant substrates and, in many cases, controlled by regulatory elements situated proximate to catabolic genes. For SIGEX to be high throughput, we constructed an operon-trap gfp-expression vector available for shotgun cloning that allows for the selection of positive clones in liquid cultures by fluorescence-activated cell sorting. The utility of SIGEX was demonstrated by the cloning of aromatic hydrocarbon-induced genes from a groundwater metagenome library and subsequent genome-informatics analysis.
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