Explore the vast range of titles available.

Spatiotemporal distributions of anthropogenic radionuclides in marine surface sediments off Miyagi, Fukushima, and Ibaraki Prefectures were analyzed on the basis of data collected during the monitoring program launched by the Japanese Ministry of Education, Sports, Science and Technology in 2011 right after the Fukushima Dai-ichi Nuclear Power Plant accident began. Concentrations of 137Cs in the surface sediments varied spatially by two orders of magnitude, from 1.7 to 580 Bq kg-dry−1, and there was no obvious correlation between 137Cs concentration and the proximity of the sampling location to the accident site. The total inventory of 137Cs accumulated in the upper 3 cm of surface sediments in the monitoring area was estimated to be 3.78 × 1013 Bq, that is, 0.1–2% of the total 137Cs flux from the plant to the ocean as a result of the accident (the percentage depends on the model used to estimate the total flux). The spatial variations of 137Cs concentration and inventory depended on two main factors: the 137Cs concentration in the overlying water during the first several months after the accident and the physical characteristics of the sediments (water content and bulk density). The temporal variations of the concentrations of other anthropogenic radionuclides (90Sr, 95Nb, 110 mAg, 125Sb, 129Te, and 129 mTe) in the sediments were also investigated. Activity ratios of these nuclides to 137Cs suggest that the nuclides themselves were not homogenized before they were removed from seawater to the sediments.

The activities of artificial radionuclides in seawater samples collected off the coast of Miyagi, Fukushima, and Ibaraki Prefectures were measured as part of a monitoring program initiated by the Japanese Ministry of Education, Sports, Science and Technology immediately after the Fukushima Dai-ichi Nuclear Power Plant accident. The spatial and temporal distributions of those activities are summarized herein. The activities of strontium-90, iodine-131, cesium-134 and -137 (i.e. 90Sr, 131I, 134Cs, and 137Cs) derived from the accident were detected in seawater samples taken from areas of the coastal ocean adjacent to the power plant. No 131I was detected in surface waters (≤ 5 m depth) or in intermediate and bottom waters after 30 April 2011. Strontium-90 was found in surface waters collected from a few sampling stations in mid-August 2011 to mid-December 2011. Temporal changes of 90Sr activity in surface waters were evident, although the 90Sr activity at a given time varied widely between sampling stations. The activity of 90Sr in surface waters decreased slowly over time, and by the end of December 2011 had reached background levels recorded before the accident. Radiocesium, 134Cs and 137Cs, was found in seawater samples immediately after the accident. There was a remarkable change in radiocesium activities in surface waters during the first 7 months (March through September 2011) after the accident; the activity reached a maximum in the middle of April and thereafter decreased exponentially with time. Qualitatively, the distribution patterns in surface waters suggested that in early May radiocesium-polluted water was advected northward; some of the water then detached and was transported to the south. Two water cores with high 137Cs activity persisted at least until July 2011. In subsurface waters radiocesium activity was first detected in the beginning of April 2011, and the water masses were characterized by σt (an indicator of density) values of 25.5–26.5. From 9–14 May to 5–16 December 2011, the depths of the water masses increased with time, an indication that deepening of the isopycnal surfaces with time can be an important mechanism for the transport of radiocesium downward in coastal waters. During 4–21 February 2012, the water column became vertically homogeneous, probably because of convective mixing during the winter; the result was nearly constant values of radiocesium activity throughout the water column from the surface to the bottom (~200 m depth) at each station.

Repeated land application of dairy manure can increase soil phosphorus above crop requirements because of manure’s low nitrogen (N) to phosphorus (P) ratio (N:P < 4:1). This soil P build-up can lead to off-site P transport and impairment of surface water quality. We evaluated a treatment process to extract P from manures, called Quick Wash, integrated with a double-stage solids separation system to recover coarse and fine manure solids. The Quick Wash process uses a combination of acid, base, and organic polymers to extract and recover P from manures, improving the N:P ratio of recovered manure solids (RMS). Results showed that coarse RMS could have use as bedding materials for dairy cows, and the fine acidified RMS with N:P > 10:1 can be used as a low-P organic soil amendment. A soil incubation test showed that acidified RMS stimulated N mineralization and nitrification having higher nitrate levels than untreated dairy slurry when incorporated into soil. Our results suggest that the inclusion of Quick Wash in a dairy manure management system can improve manure’s value, lowering costs of bedding material and manure hauling, and recover P for use as fertilizer while reducing the environmental impact of land spreading manure P.

To study non-magnetic and magnetic impurity effects at the superconductor-normal metal interfaces, we have measured the differential conductance dI/dV for Josephson contacts made by vanadium (V) nanoconstrictions with a different amount of hydrogen (H) and deuterium (D) impurities, which are prepared by a mechanically controllable break junction (MCBJ) technique at low temperature. Below the superconducting transition temperature TC, we have found distinct peaks within and outside the gap, known as the sub-gap structure and an over-the-gap structure respectively, due to 5% concentration of atomic H and D on V nanocontact. Moreover, the temperature dependence of dI/dV spectra represents that both structures are survived until the critical temperature TC, which is consistent with the prediction of BCS energy gap. On the other hand, a very high concentrating phase (30atom%) behaves as a normal metal.

We construct a \"needle-anvil\" type point-contact spectrometer for spin polarization measurements, which is installed in a 4He-cryostat. Two types of piezo devices are used to control the contact size precisely between a sample ferromagnet and a superconductor. An attocube piezo-based positioner is mounted for coarse movement of the tip, while a stacked-type piezo device is used for fine control of the contact size. This enables to change the contact size between the tip and sample from sub micro-meters to atomic-size contacts continuously. By suppressing thermal flow into the sample space and mechanical vibration, we can keep the contact over hours, enabling the precision measurements. To examine the performance of the spectrometer, we study the spin polarization of polycrystalline SrRuO3 with the point-contact Andreev reflection measurements. The polarization is estimated to be ∼0.59 at the clean limit of the interface, which is consistent with previous study.

In 2014 and 2015, we examined the spatial distribution of cesium-134 (half-life: 2.06 years) from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) in marine sediments within coastal–basin areas (water depths of 40–520 m) off central Honshu Island (the main island of Japan) in the Sea of Japan. The 134 Cs concentrations in both the surface sediment (0–1 cm depth) and whole-core inventory exhibited wide variations, and were highest at the site closest to the Agano River Estuary area (6.7 Bq/kg-dry and 886 Bq/m 2 , respectively). This indicates that 134 Cs in coastal areas was delivered by riverine suspended solids (SS). Given the spatial variation in 134 Cs concentrations, we believe that 134 Cs partially migrated northeastward within ~50 km along Honshu Island (at water depths shallower than ~140 m), and southwestward, including the Sado Basin area. This is predominantly attributable to the transport of SS by bottom currents and unsteady downward delivery onto the steep slopes of the basin. The total amount of 134 Cs in the study area in 2014 was estimated at approximately 0.6 TBq (decay-corrected to March 11, 2011, date of FDNPP accident).

We report on hydrogen (H) and deuterium (D) atoms absorption below T = 20 K in metallic palladium (Pd) via quantum tunnelling (QT). When a small bias voltage is applied between Pd nanocontacts that are immersed in liquid H2 (D2), the differential conductance spectra measured by point-contact spectroscopy change enormously. The results indicate H (D) absorption in Pd nanocontacts at the temperature where H (D) absorption due to thermal hopping process is not expected, and can be explained by QT. The QT occurs when the energy level of the potential well trapping the H (D) atom coincides with those not trapping the H (D) atom, and is assisted by phonons induced by ballistic electrons.

We report experimental study on low-temperature hydrogen (H) absorption in vanadium (V) and niobium (Nb) nanocontacts below T = 20 K using a point-contact spectroscopy (PCS) technique. When a small bias voltage is applied between both sides of nanocontacts immersed in liquid H2, the differential conductance (dI/dV) and the second derivative (d2I/dV2) are changed from those for pure V and Nb nanocontacts. Further, the spectra approach to those for a high concentrated phase of H with increasing the bias voltage. The results indicate that in-situ investigation of H absorption process from liquid H2 is possible through dI/dV and d2I/dV2 measurements using the PCS technique.

We previously reported that a high-sodium diet activates the local renin-angiotensin-aldosterone system (RAAS) in cardiovascular tissues of Dahl salt-sensitive hypertensive (DS) rats. Angiotensin-converting enzyme 2 (ACE2) is a novel regulator of blood pressure (BP) and cardiac function. The effect of blockade of aldosterone or angiotensin II (Ang II) on cardiac angiotensinogen and ACE2 in DS rats is unknown. The BP, plasma renin activity (PRA), plasma aldosterone concentration (PAC), heart weight, endothelium-dependent relaxation (EDR), and messenger RNA (mRNA) levels of collagen III, angiotensinogen, ACE, and ACE2 in the heart were measured in DS rats and in Dahl salt-resistant (DR) rats fed high or low salt diets. The rats were treated orally with or without eplerenone (100 mg/kg/d), candesartan (10 mg/kg/d), or both dugs combined for 8 weeks. A high salt diet increased BP (140%), heart/body weight (132%), and collagen III mRNA levels (146%) and decreased PRA and PAC concomitant with increased expression of cardiac angiotensinogen mRNA and decreased mRNA levels of ACE2 in DS rats. Eplerenone or candesartan significantly decreased the systolic BP from 240 ± 5 mm Hg to 164 ± 4 mm Hg or to 172 ± 10 mm Hg, respectively ( P < .05). Eplerenone or candesartan partially improved heart/body weight and cardiac fibrosis, improved EDR and decreased cardiac ACE and angiotensinogen mRNA levels in DS rats. Candesartan increased ACE2 mRNA levels in the heart. Combination therapy normalized BP and further improved cardiac hypertrophy, fibrosis, and EDR. In DS rats, blockade of aldosterone or Ang II protects cardiac hypertrophy and fibrosis by inactivation of the local RAAS in the heart.

Magnetic materials with large magnetocaloric effect are significantly important for magnetic refrigeration. La(Fe0.88Si0.12)13 compounds are one of the promising magnetocaloric materials that have a first order magnetic phase transition. Transition temperature of hydrogenated La(Fe0.88Si0.12)13 increased up to room temperature region while keeping metamagnetic transition properties. From view point of practical usage, bonded composite are very attractive and their properties are important. We made epoxy bonded La(Fe0.88Si0.12)13 hydrides. Magnetocaloric effect was studied by measuring specific heat, magnetization, and temperature change in adiabatic demagnetization. The composite had about 20% smaller entropy change from the hydrogenated La(Fe0.88Si0.12)13 powder in 2 T. Thermal conductivity of the composite was several times smaller than La(Fe,Si)13. The small thermal conductivity was explained due to the small thermal conductivity of epoxy. Thermal conductivity was observed to be insensitive to magnetic field in 2 T. Thermal expansion and magnetostriction of the composite material were measured. The composite expanded about 0.25% when it entered into ferromagnetic phase. Magnetostriction of the composite in ferromagnetic phase was about 0.2% in 5 T and much larger than that in paramagnetic phase. The composite didn't break after about 100 times magnetic field changes in adiabatic demagnetization experiment even though it has magnetostriction.