An extreame disposition method for low-level radioactive wastes using supercritical water (3)

Disposition of low-level radioactive wastes has been performed in supercritical water with RuO₂ as a catalyst without the addition of any oxidizing materials. These wastes arose from nuclear power plants etc., constituting of nonflammable organic materials, such as fire resistant sheeting and rubber gloves. We investigated the distribution behavior of iron and cobalt attached to nonflammable organic materials, in solid, liquid and gas phases during the decomposition of this method. The distributions of these elements under various conditions (initial amounts) were determined by using their radioisotopes as simulated low-level radioactive wastes in order to ease the detection of trace amounts of elements even in solid and gas phases. Iron and cobalt were found only in the solid phase when non-radioactive iron hydroxide was added as a precipitation reagent before the supercritical-water reaction.     

Pollution of montane soil with Cu, Zn, As, Sb, Pb, and nitrate in Kanto, Japan

Soil cores and rainwater were sampled under canopies of Cryptomeria japonica in four montane areas along an atmospheric depositional gradient in Kanto, Japan. Soil cores (30 cm in depth) were divided into 2-cm or 4-cm segments for analysis. Vertical distributions of elemental enrichment ratios in soils were calculated as follows: (X/Al)_i/(X/Al)_BG (where the numerator and denominator are concentration ratios of element-X and Al in the i- and bottom segments of soil cores, respectively). The upper 14-cm soil layer showed higher levels of Cu, Zn, As, Sb, and Pb than the lower (14-30 cm) soil layer. In the four areas, the average enrichment ratios in the upper 6-cm soil layer were as follows: Pb (4.93) ≥ Sb (4.06) ≥ As (3.04) > Zn (1.71) ≥ Cu (1.56). Exogenous elements (kg/ha) accumulated in the upper 14-cm soil layer were as follows: Zn (26.0) > Pb (12.4) > Cu (4.48) ≥ As (3.43) ≥ Sb (0.49). These rank orders were consistent with those of elements in anthropogenic aerosols and polluted (roadside) air, respectively, indicating that air pollutants probably caused enrichment of these elements in the soil surface layer. Approximately half of the total concentrations of As, Sb, and Pb in the upper 14-cm soil layer were derived from exogenous (anthropogenic) sources. Sb showed the highest enrichment factor in anthropogenic aerosols, and shows similar deposition behavior to NO₃⁻, which is a typical acidic air pollutant. There was a strong correlation between Sb and NO₃⁻ concentrations in rainfall (e.g., in the throughfall under C. japonica: [NO₃⁻] = 21.1 [dissolved Sb], r = 0.938, p < 0.0001, n = 182). Using this correlation, total (cumulative) inputs of NO₃⁻ were estimated from the accumulated amounts of exogenous Sb in soils, i.e., 16.7 t/ha at Mt. Kinsyo (most polluted), 8.6 t/ha at Mt. Tsukuba (moderately polluted), and 5.8 t/ha at the Taga mountain system (least polluted). There are no visible ecological effects of these accumulated elements in the Kanto region at present. However, the concentrations of some elements are within a harmful range, according to the Ecological Soil Screening Levels determined by the U.S. Environmental Protection Agency.     

Transition in fouling mechanism in microfiltration of a surface water

The main disadvantage of membrane filtration is membrane fouling, which remains as the major obstacle for more efficient use of this technology. Information about the constituents that cause fouling is indispensable for more efficient operation. We examined the changes in both foulant characteristics and membrane morphology by performing the pilot-scale filtration test using one microfiltration membrane. During the operation, we cut the membrane fibers three times, and the components that caused irreversible fouling were extracted by acid or alkaline solution. We found that the characteristic of inorganic matter extracted by acid solution completely differed depending on the filtration period. A large amount of iron was extracted in the second chemical cleaning, while manganese was the dominant component of the extracted inorganic matter in the third chemical cleaning. The analysis of Fourier transform infrared (FTIR) and cross polarization magic angle spinning carbon-13 (CPMAS (13)C) nuclear magnetic resonance (NMR) demonstrated that the contribution of humic substances and carbohydrate in the organic foulant had increased as fouling developed. The changes in the major foulant have no relation with the fluctuation in feed water. The analysis of membrane morphology illustrated that the cake layer started to build up after the blockage of membrane pores. Based on the above results, we hypothesized the following fouling mechanism: the pores were covered or narrowed with relatively large particles such as iron, carbohydrate or protein; small particles such as manganese or humic substances blocked the narrowed pores; and finally an irreversible cake layer started to build up on the membrane surface.     

Physicochemical properties of amorphous clarithromycin obtained by grinding and spray drying

In order to characterize the amorphous clarithromycin (CAM) obtained by grinding and spray drying, physicochemical properties (crystallinity, thermal behavior, stability and solubility parameters) were evaluated. From powder X-ray diffraction, it was estimated that the crystalline state of CAM was changed into an amorphous state by grinding and spray drying. In differential scanning calorimetry measurements, both broad and sharp peaks for crystallization were observed in ground samples, whereas spray dried samples showed one broad peak due to crystallization. As to the stability test under high humidity, structural difference was confirmed between ground CAMs and spray dried CAM. The heat of dissolution of ground CAMs was greater than that of intact CAM. In the solubility parameter measurement, the increase of the special term, deltas, indicated that the energy change was due to the polarity of the surface energy of the powder particles by grinding.     

Effect of Excess PbO on the Densification of PLZT Ceramics

The densification behavior and electrical properties of PLZT ceramics as a function of excess PbO in the starting powder have been investigated. The hot-pressed PLZT ceramics, prepared from powders containing 0% to 4% excess PbO, were transparent, and their electrical properties were similar in general. PLZT with PbO deficiency up to 1.4 mol% from stoichiometry can be regarded as a single phase-PLZT.     

A new method for evaluation of motor deficits in 3-acetylpyridine-treated rats

BACKGROUND: approximately one-third of patients with Alzheimer's disease (AD) respond favourably to the anticholinesterase tacrine, but the drug's usefulness is marred by a high incidence of side-effects. OBJECTIVE: to discover if AD patients with white matter low attenuation (WMLA) represents a subgroup that responds differently to tacrine from those with no WMLA. DESIGN: the results come from a combination of double-blind and open studies. Seventy-two AD patients prescribed tacrine in our centre were divided into two groups according to the presence or absence of WMLA on brain CT scans. We compared the rate of response to and withdrawal from tacrine between the groups. Response was defined as an improvement in the Mini-Mental State Examination score of three or more points at 3 months. RESULTS: 18 of the 72 patients were found to have WMLA. There was no significant difference in the proportion of patients responding to tacrine in each group (28.5% in those with WMLA and 31% in those without), but the rate of withdrawal from tacrine did differ: 11 patients with WMLA (61%) had to be withdrawn prematurely, compared with 14 patients (26%) in the group without evidence of WMLA (P = 0.015). CONCLUSION: AD patients with WMLA can still respond to tacrine, although the rate of withdrawal from treatment is much higher in such patients.     

Formation mechanism of ZrSiO4 powders

The formation mechanism of ZrSiO₄ powders from ZrO₂ and colloidal SiO₂ sols has been studied. The change in the ZrSiO₄ yield rate with seeding and non-seeding has also been investigated. The induction period of the ZrSiO₄ yield-rate curve corresponded to the n=1 region, a simple nucleation region, on the Avrami plot. The n=1 region was a rather wide range at 1200–1300°C and the nucleation reaction was promoted in this temperature range. It was found that the ZrSiO₄ yield rate became high, even if seeding was not used, when the heating rate was controlled at less than 1 °C min^–1.     

The positional distribution of dioleoyl-palmitoyl glycerol influences lymph chylomicron transport, composition and size in rats

The effects of 1,3-dioleoyl-2-palmitoyl glycerol (OPO) on lymph chylomicron transport, composition and size in rats were investigated in comparison with 1,2-dioleoyl-3-palmitoyl glycerol (OOP). The OPO and OOP were prepared by enzymatic transesterification reactions. The concentrations of OPO and OOP in the preparations were 65.7 g/100 g, and the composition of fatty acids was similar for each. The OPO preparation contained triacylglycerols with 76.6% of the palmitic acid in the sn-2 position, whereas 100% of the oleic acid was esterified to the sn-2 position in the OOP preparation. Rats were infused with lipid emulsion containing 150 g/L of OPO or OOP via a stomach catheter. Lymph was collected through the mesenteric lymphatic trunk at 1-h intervals for 12 h. Collected lymph chylomicrons were analyzed for triacylglycerol, fatty acids, apolipoprotein A-I and particle size. The maximum transport rates of triacylglycerols in the OPO group were higher than those in the OOP group. The overall absorption of triacylglycerols, palmitic acid and oleic acid in the OPO group was also higher than that in the OOP group. In the chylomicrons, 60-70% of the fatty acids at the sn-2 position of the infused triacylglycerol was transported at the original position. The transport rates of dioleoyl-palmitoyl glycerol in the OPO group were higher than those in the OOP group. The transport rates of apolipoprotein A-I did not differ between groups, whereas the mean diameter of the chylomicrons in the OPO group was larger than that in the OOP group. These results indicate that OPO is absorbed and transported more effectively than OOP.     

Development of a compact high-density microbial hydrogen reactor for portable bio-fuel cell system

The development of a compact high-density microbial reactor for hydrogen production is described with possible implications to use as a portable bio-fuel cell system. To construct the compact bioreactor, mainly, the cell density and immobilization methods were optimized in this paper. The encapsulation of hydrogen producing bacterium, Escherichia coli strain MC13-4, in alginate gel beads provided approximately three-fold increase in hydrogen production in comparison with the free cell suspension. The immobilized cells (cell density; O.D. 100) and 500 mM glucose solution were packed into a 20 mL glass bottle that was connected to the fuel cell. This system has generated electricity of over 20 mW for 20 min.