Determination of a strong organic ligand dissolved in seawater: Thorium-complexing capacity of oceanic dissolved organic matter

Studies have been made of loose water tritium (LWT) distribution and behavior in the soil samples taken from the region within a radius of 2 km to the HWRR stack of CIAE. The analytical results show that the LWT concentrations in most soil samples of the region are in the range from 24.8 Bq/l (3.6 Bq/kg) to 116 Bq/l (16.0 Bq/kg) with an average value of 58.1±24.8 Bq/l (10.3±4.5 Bq/kg). There are two areas with a higher LWT content; the first one (4.61 · 10⁴ m²) is located near HWRR with ahighest LWT concentration of 287 Bq/l (55.8 Bq/kg) and the second one (3.27 ·10⁵ m²) is located near Lab. A with a highest LWT concentration of 2.35 · 10⁴ Bq/l (2.56 · 10³ Bq/kg). It is estimated that the LWT inventories deposited in soil of the two areas are about 1.52 · 10⁹ Bq and 1.42 · 10¹⁰ Bq, respectively. The analytical results have been evaluated by comparing the possible tritium intake of the human body with the annual limit of intake recommended by ICRP, it can be concluded that the operations of all the nuclear facilities releasing tritium in CIAE are safe without causing any notable tritium contamination.     

Sample enrichment by using monolithic precolumns in microcolumn liquid chromatography

An on-line sample enrichment system was designed using monolithic precolumns in microcolumn LC. The monolithic ODS capillary columns were prepared via in situ sol-gel processes. The enrichment efficiency of the monolithic columns was tested by using phthalates as the analytes. The relative standard deviations (n = 6) for the retention time, peak area and peak height were between 0.4 and 1.2%, 0.9 and 5.5% and 0.4 and 3.9%, respectively. The system was linear (R2 > 0.99) within the working sample concentration and sample volume ranges. Comparing to 0.2 microl injection with a typical sample injector, the theoretical plate number of a same separation column was increased by 3-6-fold when the precolumn unit was used for sample injection. The recoveries of the analytes were between 88 and 120%, and the sample volume that could be injected into the system was increased up to 5000-fold. The limits of detection were improved by more than 2000-fold and were between 0.21 and 0.87 ng ml(-1) even with a UV absorbance detector. This system was applied to the determination of phthalates contained in laboratory distilled water and tap water samples.     

Synthesis, characterization and FET properties of novel dithiazolylbenzothiadiazole derivatives

Dithiazolylbenzothiadiazoles easily obtained have high electron affinity and the FET device of a trifluoromethylphenyl derivative exhibited a good n-type performance with high electron mobility.     

Incorporation of lipid domains in Cerasome, a morphologically-stable organic-inorganic vesicular nanohybrid

To extend the concept of the Cerasome, an organic-inorganic vesicular nanohybrid, this paper investigates the preparation and characterization of a “mixed” Cerasome. The system consists of a Cerasome-forming lipid 1, a cationic synthetic lipid 2, and a zwitterionic phospholipid 3. Lipid mixtures of 1 and 2 or 1 and 3 were used to prepare the mixed Cerasomes. Their lipid distributions were examined using differential scanning calorimetry (DSC), which showed that 1 and 2 (or 1 and 3) were phase-separated in the mixed Cerasomes. These results seem to be mainly attributable to the polymerizable nature of 1. Results of scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX) showed that 1 and 3 were both incorporated into a single Cerasome, not macroscopically separated to form separate vesicles from each lipid component. Mixed Cerasomes of 1 and 2 showed high morphological stability against a membrane-solubilizing surfactant, incorporating up to 70% of 2. On the other hand, the mixed Cerasomes from 1 and 3 were less stable than the mixed Cerasomes from 1 and 2. This relative instability might be attributable to differences between the mixed Cerasomes from 1 and 2 and 1 and 3 in terms of their vesicular sizes, lipid domain sizes, and their relative effectiveness for siloxane network formation. These results strongly support the formation of mixed Cerasomes that have lipid domains in-plane. Systems described in this study are useful to prepare variously mixed Cerasomes that have different surface functionalities and in-plane lipid distribution, but which have high morphological stability.     

Theoretical Study of Clathrate Hydrates with Multiple Occupation

In this work, the electronic, structural, dynamic andthermodynamic properties of structure II, H and tetragonalAr clathrate hydrates have been calculated and the effectof multiple occupancy on their stability has been examinedusing first-principles and lattice dynamics calculations.The dynamic properties of these clathrates have beeninvestigated depending on the number of guest moleculesin a clathrate cage. It has been found that selectedhydrate structures are dynamically stable. The calculatedcell parameters are in agreement with experimental data.We also report the results of a systematic investigationof cage-like water structures using first-principles calculations. Ithas been observed that Ar clusters can be stabilized indifferent water cages and the stability is strongly dependenton the number of argon atoms inside the cages.     

Cross-chiral examinations of molecular enantioselective recognition by fast atom bombardment mass spectrometry: Host–guest complexations between chiral crown ethers and chiral organic ammonium ions

Using fast atom bombardment (FAB) mass spectrometry (MS), cross-chiral relationships were confirmed for the first time for the diasteromeric host-guest complexations between the chiral crown ether host (1) and the chiral organic ammonium ion guest (2) on the basis of the relative peak intensities (RPI). Both host–guest combinations (R, R, R, R) – 1, (R) – 2 and (S, S, S, S) – 1, (S) – 2 obviously provided larger RPI values than the combination of both (R, R, R, R) – 1, (S) – 2 and (S, S, S, S) – 1, (R) – 2 by a factor of 1.6 as an averaged value: 1.87 (n = 4)/1.16 (n = 4) = 1.6. These results are consistent with the expected stabilities of the host-guest complexations by CPK model examinations. Successfully observed cross-chiral examinations strongly suggest a potentially useful FABMS/RPI methodology for rapidly searching newly designed and synthesized crown ether-like host compounds with a higher degree of enantioselectivity.     

Plutonium isotopes in the Sea of Japan

Plutonium isotopes in the Sea of Japan were determined to assess radioactive contamination. Concentrations of ^239,240Pu in surface water of the Sea of Japan were maintained at a constant level over the past two decades in contrast to ¹³⁷Cs. A median value of surface ^239,240Pu in the Sea of Japan in this period was 5.6 mBq/m³ with the range between 2.1 and 14.0 mBq/m³, which is slightly higher than that in the western North Pacific. The vertical distribution of ^239,240Pu showed a surface minimum, a subsurface maximum and gradual decrease with increasing depth. The ²⁴¹Pu/^239,240Pu activity ratios in water columns were almost constant except for surface water. In regard to ^239,240Pu in surface water of the Sea of Japan, these findings suggest that rapid recycling of deeper plutonium occurs in the Sea of Japan due to deep convection in winter and biogeochemical processes such as particle scavenging and remineralization.     

Plutonium in seawater of the Pacific Ocean

The present plutonium levels in the Pacific Ocean are summarized. The ^239,240Pu concentrations in surface seawaters in the early 2000s were in the range of 1.5 to 9.2 mBq·m⁻³ in the North Pacific and 0.8 to 4.1 mBq·m⁻³ in the South Pacific. There is no marked difference of surface ^239,240Pu distributions between the North and South Pacific subtropical gyres. The vertical profile of ^239,240Pu in the South Pacific was the similar pattern to that in the North Pacific, which is controlled by biogeochemical processes. The ^239,240Pu inventories (down to 2300 m) in the North Pacific are generally greater than that in the South Pacific, which reflects the geographical distribution of global fallout and effect of close-in fallout in the Marshall Islands.     

Plutonium isotopes in the surface air in Japan: Effect of Chernobyl accident

Plutonium isotope concentrations in the surface air at Tsukuba, Japan are reported during the period from 1981 to the end of 1986. The^239,240Pu concentration in the surface air, which showed a marked seasonal variation with a spring maximum and fall minimum, decreased until the end of 1985 according to the stratospheric residence time of 1.15 years. In May 1986, elevated^239,240Pu concentrations with high²³⁸Pu/^239,240Pu activity ratios were observed. The serial trend of plutonium concentration in the surface air is similar to the concentrations of the Chernobyl-released radionuclides. These findings suggest that a significant part of the plutonium in the surface air in May 1986 was due to the Chernobyl fallout. The size distribution of plutonium bearing particles indicates that plutonium isotopes were mechanically released in the Chernobyl accident. The surface air concentration of plutonium from the Chernobyl accident was much lower than the concentrations of the volatile fission products, and increased the monthly mean^239,240Pu concentration by only 0.03 Bqm^–3.     

Combined analysis of microwave and infrared spectra of methyl iodide: rotational and l-type doubling constants of the v5, v3+v6 and v2 states

The rotational constant B and the l-type doubling constant q were determined for the v₅, v₃+v₆ and v₂, states of CH₂I from the microwave transition frequencies, in combination with the infrared data previously reported. Since these vibrational states were coupled through the Fermi resonance and the xy-type E-E and A₁-E Coriolis resonances, the analysis was made by setting up and solving the complete form of the secular determinants of the energy matrices. The rotational and l-type doubling constants were determined as B₅, = 0.250 173 cm^?1, B₃₆ = 0.247 600 cm^?1, B₂ = 0.249 369 cm^?1, q₅ = ?0.000 027 cm^?1 and q₃₆ = ?0.000 179 cm^?1, which are unperturbed by Fermi and Coriolis interactions. Other band constants for v₅ and v₃+v₆ were also refined in accordance with the new values of B₅ and B₃₆. The present study indicated that the combined analysis of microwave and infrared spectral data was useful for the precise determination of vibration-rotation, levels in the perturbed system.