Crude oil bioremediation field experiment in the Sea of Japan

Experimental bioremediation of crude oil was conducted for approximately 3 months in the intertidal zone of the Sea of Japan, Hyogo Prefecture. Artificial mixtures of weathered Arabian light crude oil and sand taken from the experimental site were wrapped in polyester net envelopes. The envelopes were placed in drum-shaped acrylic vessels with perforated sides to facilitate seawater exchange. The vessels were laid in the intertidal area. Slow release nitrogen and phosphorus synthetic fertilizer granules were added to the oil-sand mixtures in three different amounts. Some oil-sand mixtures were unfertilized controls. The oil-sand mixtures were periodically sampled and changes in the composition of the residual oils were monitored. Oil samples were subjected to gas chromatography coupled with mass spectrometry for analysis of some representative semi-volatile aliphatic and aromatic compounds. All values for each analyte were normalized against that of hopane to evaluate the extent of oil biodegradation. Significant increases in the concentrations of both nitrogen and phosphorus were found in the fertilized sections in accordance with the amounts of added fertilizers. Although significant natural attenuation of oil was observed in the unfertilized sections, fertilization stimulated the degradation rate of the oil in the early stage of the experimental term. The extent of the oil biodegradation increased as the amount of added fertilizer increased. However, the final degradation efficiencies for each oil component in the fertilized sections were not significantly different from those in the unfertilized sections, and the degradation of each oil component had almost ceased after 6 weeks. We conclude that excessive amounts of macronutrients are required to accelerate oil biodegradation and that fertilization is only effective in the early stages.     

On the low frequency impedance probe in the ionosphere

A low frequency impedance probe designed to detect the ion-electron hybrid resonance in the ionospheric plasma is studied. Firstly, the effect of finite resistance of an ion sheath surrounding a probe is analyzed for the case of a cylindrical probe and quantitative insight into this is given. Secondly, the dissipations due to warm plasma effects which appear in the actual experiment flown aboard a space vehicle are discussed. These depend upon the dimensions of the probe system and the velocity of the system relative to the mean thermal velocity of charged particles. Analyses are then carried out for a simple planar grid model using electrostatic and hydrodynamic approximations.     

Correlation of the Hakkoda–Kokumoto Tephra, a widespread Middle Pleistocene tephra erupted from the Hakkoda Caldera, northeast Japan

Abstract A Middle Pleistocene widespread tephra referred to here as Hakkoda–Kokumoto Tephra (Hkd–Ku) has been newly recognized. Hkd–Ku, derived from the Hakkoda Caldera located in northernmost Honshu Is. of northeast Japan, covers much of Honshu Is. At the type locality in the proximal area, Hkd–Ku comprises Plinian pumice deposits and an immediately overlying ignimbrite. The fine vitric ash nature of the distal ash‐fall deposits of Hkd–Ku suggests that they are coignimbrite ash‐fall deposits. Hkd–Ku was identified using a combination of refractive indices and chemical compositions of major, trace and rare earth elements of glass shards, heavy mineral content, refractive indices of orthopyroxene and paleomagnetic polarity. On the basis of these properties, Hkd–Ku was identified in Oga and Boso Peninsulas and Osaka Plain, 830 km southwest of the source. Stratigraphic positions in Boso Peninsula and Osaka Plain within marine sediments that have a reliable chronology based on oxygen‐isotope, and litho‐, bio‐, magneto‐ and tephrostratigraphy indicate that the age of Hkd–Ku is ca 760 ka, positioned in the transition between marine oxygen‐isotope stages 19.1 and 18.4. The widespread occurrence of Hkd–Ku providing a tie line between many different Pleistocene sections over a distance of 800 km is a key marker horizon in the early part of the Middle Pleistocene. This tephra gives a time control point of ca 760 ka to marine sediments in the Oga Peninsula – where no datum plane exists between the Brunhes–Matuyama chron boundary and oxygen‐isotope stage 12 – and to the volcanostratigraphy of the Hakkoda Caldera. The distribution of Hkd–Ku showing emplacement of coignimbrite ash‐fall deposits in the area 830 km southwest of the source emphasizes the upwind transport direction, relative to the prevailing westerly winds, typical of other coignimbrite ash‐fall deposits in the Japanese islands.     

The stability and equation of state for the cotunnite phase of TiO2 up to 70 GPa

The stability and equation of state for the cotunnite phase in TiO₂ were investigated up to a pressure of about 70 GPa by high-pressure in situ X-ray diffraction measurements using a laser-heated diamond anvil cell. The transition sequence under high pressure was rutile → α-PbO₂ phase → baddeleyite phase → OI phase → cotunnite phase with increasing pressure. The cotunnite phase was the most stable phase at pressures from 40 GPa to at least 70 GPa. The equation of state parameters for the cotunnite phase were established on the platinum scale using the volume data at pressures of 37–68 GPa after laser annealing, in which the St value, an indicator of the magnitude of the uniaxial stress component in the samples, indicates that these measurements were performed under quasi-hydrostatic conditions. The third-order Birch-Murnaghan equation of state at K ₀′ = 4.25 yields V ₀ = 15.14(5) cm³/mol and K ₀ = 294(9), and the second-order Birch-Murnaghan equation of state yields V ₀ = 15.11(5) cm³/mol and K ₀ = 306(9). Therefore, we conclude that the bulk modulus for the cotunnite phase is not comparable to that of diamond.     

Adjustable vertical vibration isolator with a variable ellipse curve mechanism

This paper presents a passive vertical quasi‐zero‐stiffness vibration isolator intended for relatively small objects. The present isolator has features of compactness, long stroke, and adjustability to various load capabilities. To realize these features, we use constant‐force springs, which sustain constant load regardless of their elongation, and propose a variable ellipse curve mechanism that is inspired by the principle of ellipsographs. The variable ellipse curve mechanism can convert the restoring force of the horizontally placed constant‐force springs to the vertical restoring force of the vibration isolator. At the same time as converting the direction, the vertical restoring force can be adjusted by changing the ratio of the semi‐minor axis to the semi‐major one of the ellipse. In this study, a prototype of a class of quasi‐zero‐stiffness vibration isolator with the proposed variable ellipse curve mechanism is created. Shaking table tests are performed to demonstrate the efficacy of the present mechanism, where the prototype is subjected to various sinusoidal and earthquake ground motions. It is demonstrated through the shaking table tests that the prototype can reduce the response acceleration within the same specified tolerance even when the mass of the vibration isolated object is changed. Copyright © 2017 John Wiley & Sons, Ltd.