Search

We studied the stepwise formation constants (β) of water-soluble diglycolamide (DGA) and dioxaoctanediamide (DOODA) for the mutual separation of Ln in a solvent extraction system. TODGA (N,N,Nʹ,Nʹ-tetraoctyl-diglycolamide) and DOODA(C8) (N,N,Nʹ,Nʹ-tetraoctyl-dioxaoctanediamide) exhibit opposite behaviors in extracting both light and heavy Ln through Ln-patterns. Metal complexes of two- and three-folding with water-soluble DOODA and DGA, respectively, were found, and each β value was calculated using distribution ratios. Taking β, their distribution ratio, D, and separation factor, SF, values into consideration, the suitable separation conditions (aqueous phase: 30 mM DOODA(C2) in 1 M HNO3; organic phase: 0.1 M TODGA in n-dodecane) of multistage extraction (10 × 10 extraction using aqueous and organic phases, including one sample solution) were determined. In this study, La, Pr, and Nd were mainly present in the aqueous phase, whereas Sm–Dy existed in the organic phase. Although these two groups can be easily separated into two phases, the resolution, Rs, values provide for little mutual separation between La–Nd and Sm–Dy under the present conditions.

We investigated the chemical behavior of lanthanides (Ln) by multistage extraction. Using 10 aqueous phases with Ln and 3 organic phases, we drew the breakthrough curves for light and middle Ln. Our study reveals that the limit of metal extraction depends on their D values and the metal concentration employed in experiments. From the multistage extractions of 15 stage aqueous phases and 15 stage organic phases, three curves (extraction curves, back-extraction curves, and separation curves) were obtained. Setting appropriate conditions, adequate separation of light Ln from middle ones can be achieved. As an example, under the condition of the separation curve experiment (aqueous phase: 0.5 M HNO3, organic phase: 0.1 M TDDGA (N,N,N',N'-tetradecyl-diglycolamide) in n-dodecane), the recovery of more than 99% of Sm in the organic phase with less than 1% of Nd can be obtained, even in the case of two metals adjacent to each other in the Ln series.

To achieve trichotomic separation of light lanthanides (Ln), heavy Ln, and Am, batchwise multi-stage extractions using N,N,N′,N′-tetraoctyl-diglycolamide (TODGA) extractant from organic acids are studied. This technique has the advantages of both solvent extraction and chromatography, which enable successive separation and management of large volumes of aqueous solutions. Malonic acid (M-Acid) is used as the main component of the aqueous phase. It is clear that the separation factor for Nd/Am from M-Acid and that for La/Am from M-Acid + HNO3 are both around 30, thus we plan to conduct these separations.

The mutual separation of lanthanides has been studied by multi-stage extraction using an extractant, DGA (diglycolamide) compounds. N,N,N',N'-tetraoctyl-DGA (TODGA) has a high extractability to lanthanides and a relatively high separation factor (SF) between Dy and Nd (SF of over 20) from HNO3 media. Complete separation with such SF values can be achieved by multi-stage extraction. Less information on multi-stage extraction compared to batch extraction has been presented up to now. We thus conducted a basic study. By confirming the experimental data to be identical to calculations, the sample solution including both metals was employed for batchwise multi-stage extraction. Ninety-seven percent of Dy with under detection limit of Nd could be recovered into the organic phase from Nd with a ten-times higher concentration than Dy using the condition, 0.1 M TODGA/n-dodecane and 0.3 M HNO3 by the multi extraction of 9 × 9 stages for organic and aqueous phases.

New aminophosphonic acid extractants, α-(4- n -octylanilino)benzylphosphonic acid monobutyl ester (OABPM) and α-dodecylaminobenzylphosphonic acid monobutyl ester (DABPM) with different amino moiety basicities were synthesized to examine the effect of the basicity on their extraction selectivities for In(III), Ga(III), Zn(II), Cu(II), Se(IV) and Se(VI). The extraction order for metals using OABPM was In(III) > Ga(III) > Cu(II) > Zn(II), while Se(IV) and Se(VI) were not extracted. On the other hand, DABPM exhibited the reverse extraction order for Cu(II) and Zn(II). The mutual separation ability of DABPM for these metals was higher than that of OABPM as is determined by the basicity of the amino moiety of their extractants. The extraction equilibria for Ga(III) and Zn(II) with OABPM and DABPM were discussed using slope analysis. It was observed that only Ga(III)- and Zn(II)-DABPM complexes contained nitrate ions, because the phosphonic acid moiety of DABPM was hard to participate in the metal extraction.

© 2020 Elsevier B.V. In this study, we fabricated porous polyketone (PK) support membranes with high pressure resistance and low structural parameter (S) by surface modification with aromatic compounds for osmotically driven membrane process applications. The effects of surface modification of PK using aromatic compounds on the membrane structure, mechanical properties, and membrane performance were investigated. Based on an estimation of the affinity between PK and aromatic compounds using Hansen solubility parameters and mechanical properties, m-phenylenediamine (MPD) was selected as an appropriate chemical modifier for PK membranes. The PK support membranes modified with MPD (PK-MPD) had a dense structure on the bottom side. The thickness and porosity of the PK membranes were changed by the treatment temperature. As a result, polyamide (PA)/PK-MPD thin film composite membranes showed superior pressure resistance in reverse osmosis. PA/PK-MPD modified at 110 °C possessed the highest pressure resistance of 21 bar, which was 3.5 times higher than that of the PA/untreated PK membrane, while maintaining a high water flux of 19.4 L m−2 h−1 in FO. This performance overcame the trade-off relationships between pressure resistance and FO flux and between pressure resistance and S value.

Development of the solvent extraction and direct electrodeposition processes is an important task for the volume reduction of secondary wastes. The extraction behavior of Pd(II) using methylimino-bis- N , N -dioctylacetamide (MIDOA) in three different diluents (acetophenone; AP, 1,2-dichloroethane; DCE, and 1-octanol; OC) was investigated in this study. From the slope analysis, it was revealed that the extraction mechanism of Pd(II) was based on the following anion exchange extraction; [PdCl 4 2- ] aq + 2[MIDOA] org ⇔ [Pd(MIDOA) 2 ] org + 4[Cl - ] aq (MIDOA/AP, DCE) [PdCl 4 2- ] aq + [MIDOA] org ⇔ [Pd(Cl) 2 (MIDOA)] org + 2[Cl - ] aq (MIDOA/OC) The electrochemical behavior of the extracted Pd(II) complex in the MIDOA/AP bath was investigated by Electrochemical Quartz Crystal Microbalance (EQCM). It was revealed that Pd(II) was reduced to Pd(0) metal by a two-electron transfer and the cathodic reaction; [Pd(MIDOA) 2 ] + 2e - → Pd(0) + 2[MIDOA] was proceeded on the region between -2.38 V and -3.40 V considering from the apparent molar mass; M app =105.22 evaluated by CV/EQCM. Moreover, the alternation of Δηρ was corresponded to the locally decrease of the viscosity of the organic phase near the electrode. Furthermore, the potentiostatic electrodeposition of the extracted Pd(II) complex enabled us to recover the blackish electrodeposits, which were identified as Pd metal by SEM/EDX, XPS and XRD analyses.

We have developed a liquid-liquid countercurrent centrifugal extractor that induces Taylor vortices in the annular fluid region. To demonstrate extraction of multiple species (Nd/Sm/Eu/Gd/Dy) with N,N,N′,N′-tetraoctyl diglycolamide (TODGA), additional chemical agents, such as a surfactant (sodium bis(2-ethylhexyl) sulfosuccinate (AOT)), a synergist (nonanoic acid) and a masking agent (N,N,N′,N′-tetraethyl-3,6-dioxaoctane-1,8-diamide (DOODA(C2))) were employed. When only TODGA was utilized, extraction performance was not effective due to the insufficient dispersion even under a high rotating speed. By combining TODGA and other chemical agents, the separation performance was improved considerably in the countercurrent flow of aqueous and organic phases due to the synergistic effect and improved dispersion.

α-Radiation effect on the solvent extraction of 241Am using the solution of N,N,N′,N′-tetraoctyldiglycolamide was investigated by means of the external and internal irradiation systems. In contrast to the internal irradiation system using an actinide radionuclide as an α-particles emitter, the external irradiation with 4He2+ ions provided by an accelerator can be carried out in a reasonable timescale and without contamination with radionuclides. No significant decrease in distribution ratio was observed even after irradiation over 200 kGy in both systems. It was also confirmed that the external irradiation system could be a useful alternative to the internal irradiation.

Extraction chromatographic separation of trivalent minor actinides (MA: Am and Cm) was investigated by using solid adsorbents impregnating the lipophilic diamide-type ligands, TODGA (N,N,N′,N′-tetraoctyl-3-oxapentane-1,5-diamide) and DOODA(C8) (N,N,N′,N′-tetraoctyl-3,6-dioxaoctane-1,8-diamide). In nitric acid eluents, hydrophilic diamide-type ligands, DOODA(C2) (N,N,N′,N′-tetraethyl-3,6-dioxaoctanediamide) and TEDGA (N,N,N’,N’-tetraethyl-diglycolamide) were included for the respective adsorbents as masking agents in order to produce a synergistic effect in mutual separation of Am and Cm. The adsorption tendency of Am and Cm for the adsorbents was opposite each other, that was similar to the case of lanthanides.

A novel extractant, N,N,N′,N′,N′′,N′′-hexaalkyl-nitrilotriacetamide (NTAamide), was developed for the extraction and separation of actinides (An) and lanthanide (Ln). NTAamide has a nitrogen atom in the center of a backbone and is bonded to three acetamide groups; the nitrogen and three amide oxygen atoms can work as the donor atoms. NTAamide extracted Am and Cm with a low distribution ratio of Ln in diluted HNO3, and the separation factor (SF) for An/Ln was equal to or higher than 23.6 using 0.5 M NTAamaide/n-dodecane and 0.2 M HNO3. The addition of N,N,N′,N′-tetraethyldiglycolamide as a masking agent to the NTAamide extraction system was effective for separating Am from Cm; the maximum SF was 6.5, one of the highest SF values obtained using the HNO3 and n-dodecane system.

Precise heat-capacity measurements have been made around the smectic-–smectic- phase transition in the R–S mixture of liquid crystal MHPOBC ([1,1′-biphenyl]-4-carboxylic acid, 4′-(octyloxy)-, 4-[[(1-methylheptyl)oxy]carbonyl]phenyl ester) which exhibits ferro- and antiferroelectric phases. Ultra-low frequency ac calorimeter and high-sensitivity differential scanning calorimeter have been used. The measurements revealed the existence of quite slow relaxation near the transition. The heat-capacity anomaly accompanying the transition showed a significant increase as decreasing heat frequency in the ac method. The excess heat capacity observed for a mixture that is closest to the critical point has been analysed quantitatively.

The structures of the complex of 2,2'-(methylimino)bis(N,N-dioctylacetamide) (MIDOA) with M(VII)O(4)(-) (M = Re and Tc), which were prepared by liquid-liquid solvent extraction, were investigated by using (1)H nuclear magnetic resonance (NMR), extended X-ray absorption fine structure (EXAFS), and infrared (IR) spectroscopy. The (1)H NMR spectra of the complex of MIDOA with Re(VII)O(4)(-) prepared in the organic solution suggest the transfer of a proton from aqueous to organic solution and the formation of the H(+)MIDOA ion. The EXAFS spectra of the complexes of H(+)MIDOA with Re(VII)O(4)(-) and Tc(VII)O(4)(-) show only the M-O coordination of the aquo complexes, suggesting that the chemical state of M(VII)O(4)(-) was unchanged during the extraction process. The results from (1)H NMR and EXAFS, therefore, provide evidence of M(VII)O(4)(-)···H(+)MIDOA complex formation in the organic solution. The IR spectra of Re(VII)O(4)(-)···H(+)MIDOA and Tc(VII)O(4)(-)···H(+)MIDOA were analyzed based on the structures and the IR spectra that were calculated at the B3LYP/cc-pVDZ level. Comparison of the observed and calculated IR spectra demonstrates that an intramolecular hydrogen bond is formed in H(+)MIDOA, and the M(VII)O(4)(-) ion interacts with H(+)MIDOA through multiple C-H(n)···O hydrogen bonds.

In order to examine extraction behavior of ReO 4 - from HNO 3 aqueous solution to dodecane containing 2,2′-(imino)bis( N , N ′-dioctylacetamide) (IDOA) as an extractant, we have measured distribution ratios ( D ) by changing [HNO 3 ] under constant [IDOA] (5.00 × 10 −2 M, M = mol dm −3 ) in dodecane and also by changing [IDOA] in dodecane under constant [HNO 3 ] 0.1, 1.0, and 2.0 M. It was found that the D values decrease with an increase in [HNO 3 ] and increase with increasing [IDOA]. The decrease in D values with increasing [HNO 3 ] is considered to be due to effect of the protonation of IDOA in aqueous phase and also competitive extraction of NO 3 - with ReO 4 - from aqueous to organic phase. A plot of log D values against log [IDOA] gave the linear relationship with slope of ca. 1.03 ± 0.01 ([HNO 3 ] = 0.1 M), 1.02 ± 0.01 ([HNO 3 ] = 1.0 M) and 0.94 ± 0.01 ([HNO 3 ] = 2.0 M). These results suggest that one IDOA molecule contributes to the extraction of ReO 4 - . Effects of diluents (dodecane, toluene, dichloromethane) on the extraction of ReO 4 - with IDOA showed that IDOA exhibits higher extraction efficiencies into dodecane than toluene and dichloromethane. Furthermore, the influences of HNO 3 , H 2 SO 4 and HCl on the extraction of ReO 4 - into dodecane were examined by changing their concentrations from 0.1 to 2.0 M at [IDOA] = (5.00 × 10 −2 M). The results showed that the highest D values of ReO 4 - were observed in the H 2 SO 4 system. The effects of the concentrations of the various salts ((NH 4 ) 2 SO 4 , NH 4 Cl, and NH 4 NO 3 ) on the extraction of ReO 4 - into dodecane were also examined under constant [IDOA] (3.00 × 10 −2 M) and [acid] (0.1 M). It was found that the D values of ReO 4 - decrease with an increase in the concentrations of salts in the aqueous phase. These results suggest that anionic species ( SO 4 2 - , Cl − , NO 3 - ) are extracted with ReO 4 - from aqueous to organic phase. This is confirmed by the extraction experiments of (NH 4 ) 2 SO 4 , NH 4 Cl, and NH 4 NO 3 in the absence of ReO 4 - using IDOA into dodecane. Hence, it was proposed that the decrease of D values with an increase in acid concentrations is due to the competitive extraction of anionic species ( SO 4 2 - , Cl − , NO 3 - ).

Mutual separation of trivalent lanthanides (Ln) and actinides (An) is a challenging study in order to dispose effectively these metals in high-level radioactive liquid waste. Both extractant and masking agent are used simultaneously in an extraction system. The strong extractants, diglycolamide (DGA) and dioxaoctane-diamide (DOODA), and several kinds of the masking agents, were employed. The four novel-synthesized aminopolyacetamide compounds, namely, nitrilotriacetamide (NTAamide), hydroxypropane-triacetamide (Citricamide), ethylenediamine-tetracetamide (EDTAamide), and diethylenetriamine-pentacetamide (DTPAamide), were also examined. It can be seen that these compounds has more affirmative to heavy Ln than light ones and mutual separation factors by addition of these compounds are slightly high.

The mutual separation of Am, Cm and lanthanides (Ln) by the hydrophilic and lipophilic ligands present in both aqueous and organic phases was studied. The hydrophilic ligands used here are DTPA(diethylene-triamine-N,N,N’,N’’,N’’-pentaacetic acid), malonamide, amic acid, TEDGA(N,N,N’,N’-tetraethyl-diglycolamide) and DOODA(C2) (N,N,N’,N’-tetraethyl-3, 6-dioxaoctanediamide) and four types of extractants, TODGA (N,N,N’,N’-tetraoctyl-diglycolamide), TDdDGA (N,N,N’,N’-tetradodecyl-diglycolamide), DOODA(C8) (N,N,N’,N’-tetraoctyl-3, 6-dioxaoctanediamide) and DOODA(C12) (N,N,N’,N’-tetradodecyl-3, 6-dioxaoctanediamide). DOODA(C8, 12) can extract light lanthanides with high D values into the organic phase. On the other hand (TO, TDd)DGA shows the opposite trend for Ln extraction. The high separation factor, over 1000, between D for La and that for Gd can be seen in the extraction using the extractant, TDdDGA, and DOODA(C2) as the masking agent in the aqueous phase. The separation factors for Am/Cm by DOODA(C8, C12) and (TO, TDd)DGA are 1.51-1.94, while values over 3 can be obtained by the conditions introduced in this work.

To investigate which of ammonium (NH(4)(+)) or nitrate (NO(3)(-)) is used by plants at gradient sites with different nitrogen (N) availability, we measured the natural abundance of (15)N in foliage and soil extractable N. Hinoki cypress (Chamaecyparis obtusa Endlicher) planted broadly in Japan was selected for use in this study. We estimated the source proportion of foliar N (NH(4)(+) vs. NO(3)(-)) quantitatively using mass balance equations. The results showed that C. obtusa used mainly NH(4)(+) in N-limited forests, although the dependence of C. obtusa on NO(3)(-) was greater in other NO(3)(-)-rich forests. We regarded dissolved organic N (DON) as a potential N source because a previous study demonstrated that C. obtusa can take up glycine. Thus we added DON to our mass balance equations and calculated the source proportion using an isotope-mixing model (IsoSource model). The results still showed a positive correlation between the calculated plant N proportion of NO(3)(-) and the NO(3)(-) pool size in the soil, indicating that high NO(3)(-) availability increases the reliance of C. obtusa on NO(3)(-). Our data suggest the shift of the N source for C. obtusa from NH(4)(+) to NO(3)(-) according to the relative availability of NO(3)(-). They also show the potential of the foliar delta(15)N of C. obtusa as an indicator of the N status in forest ecosystems with the help of the delta(15)N values of soil inorganic and organic N.

In order to evaluate the extraction property of new extractants, diglycolamide (DGA) compounds, we investigated the maximum extraction of di-, tri-, and tetravalent metal ions using nitric acid and n-dodecane. The limits of metal concentration (LOC) for Ca(II), Nd(III) and Zr(IV) in the organic phase are strongly influenced by HNO3 and the extractant concentration. For the purpose of enhancing the LOC value, we employed a modifier of the solvent, N,N-dihexyl-octanamide (DHOA) and DGA with a long alkyl chain, and examined the results. It was evident that LOC increased with the DHOA concentration and the length of the alkyl chain attached to the N atom of DGA. The stoichiometric values of LOC(Zr) estimated from the extraction reaction were confirmed by using the extraction condition: tetraoctyl-DGA/1 M DHOA + n-dodecane and 3 M HNO3.

The detailed study on the extraction capacity of N , N , N ′, N ′-tetraalkylderivatives of diglycolamide (DGA) was performed by using the novel analytical method, which determines the limit of metal concentration in the organic phase (LOC). The analytical results suggest that LOC of Nd(III) by N , N , N ′, N ′-tetraoctyl-diglycolamide (TODGA) depends on HNO 3 concentration and temperature. In order to increase LOC and suppress the third liquid phase, the modifier, N , N -dihexyl-octanamide (DHOA) of the aliphatic diluent was employed and its effect was investigated. The modifier can raise the LOC value, and it is noteworthy that LOC corresponds to the stoichiometric value, which is obtained by the extraction reaction, by using the extraction solvent of 0.1 M TODGA—(0.5–1 M) DHOA in n-dodecane. This condition suppresses the third liquid phase. In the absence of modifier, the relation of several DGA based compounds with LOC was investigated. It is confirmed that LOC using N , N , N ′, N ′-tetradodecyl-diglycolamide (TDdDGA), whose extractant has the longest alkyl chain in this work and forms hardly the third liquid phase, reaches to the stoichiometric value.

The extraction of 75 elements by N,N,N′,N′-tetraoctyl-3-oxapentanediamide (TODGA) from nitric acid to n-dodecane was investigated and discussed concerning distribution ratios (D) of metal ions and their ionic radii. The extractability for elements depends strongly on their oxidation state. Monovalent and pentavalent ions were not extractable. In divalent metal extraction, Ca(II) (ionic radius: 100 pm) showed the highest D-value and the D decreased with increase or decrease of the ionic radius. Trivalent and tetravalent ions with ionic radii of 87–113 and 83–94 pm, respectively, showed the D over 1000, and the extracted chemical forms were determined to be M(TODGA)3(NO3)n or M(TODGA)4(NO3)n (n = 3 or 4). The oxonium ions with higher oxidation states than tetravalent one forms the complicated metal-complex with TODGA, and the number of TODGA associated in those extraction reactions was confirmed to be two at most.

Countercurrent chromatographic separation of hippuric acid (HA) and related compounds was performed using the cross-axis coil planet centrifuge equipped with a pair of eccentric coil assemblies mounted in an off-center position. Partition coefficients of HA and a set of related compounds were determined on a polar two-phase solvent system composed of methyl t-butyl ether, 1-butanol, acetonitrile and aqueous 0.1% trifluoroacetic acid at various volume ratios. The optimal volume ratio of 1 : 0 : 0 : 1 was successfully used to resolve p-amino HA, HA, p-methyl HA, and (±)-mandelic acid by the lower aqueous phase mobile, and benzoic acid, p-methyl HA and HA by the upper organic phase mobile.

Actinide(III), (IV), (V) and (VI) ions were extracted by N,N′-dimethyl-N,N′-dihexyl-3-oxapentanediamide (DMDHOPDA) and thenoyltrifluoroacetone (HTTA). The extraction behaviors suggested the possibility of the mutual separation, and the convenient separation method of actinide ions (III), (IV), (V) and (VI) without reducing and oxidizing agents was studied. Th(IV) was extracted from the aqueous phase by HTTA (5 mM in toluene) in the first step. The Am(III) and U(VI) ions can be extracted by 1 and 20 mM DMDHOPDA in toluene, and the Np(V) ion can be extracted into nitrobenzene with 100 mM DMDHOPDA in the last step. The residual activities in the aqueous phase were much lower than the initial activities. These activities in the fractions were confirmed by the gamma- and the alpha-spectrometry. The one-through and rough separation is advanced, and in case of the fine isolation of actinide elements, each fraction should be purified in more detail.

To evaluate the anti-pathogen activity of chitinases, we developed a new method for measuring the lytic activity, and investigated the correlation of the lytic activity with the enzymatic properties by using four chitinase isozymes, Chitinases E, F, H1 and G, which had been purified from yam tubers by column chromatography. Chitinases E, F and H1 had high lytic activity against the plant pathogen, Fusarium oxysporum, but Chitinase G did not. Chitinase E, which is the family 19 chitinase, was similar to Chitinases F and G in its antigenecity, but not to Chitinase H1 or H2. Chitinases H1 and H2 were recognized by the anti-Bombyx mori chitinase antibody, suggesting that Chitinases H1 and H2 are family 18 chitinases like B. mori chitinases. Chitinases E, F and H1 had two optimum pH ranges of 3-4 and 7.5-9 toward glycolchitin, but Chitinase G had only one optimum pH value of 5. Chitinases E, F and H1 had higher affinity to the polymer substrate, glycolchitin, than Chitinase G. These results suggest that the lytic activity of plant chitinases may be related to the chitin affinity and probably to the characteristic optimum pH value, or two values, but not related to its classification. The correlation of the lytic activity of a chitinase isozyme with its elicitor specificity is also discussed.

N,N′-ジメチル-N,N′-ジヘキシル-3-オキサペンタンジアミド(DMDHOPDA)又はN,N′-ジメチル-N,N′-ジヘキシル-3-チアペンタンジアミド(DMDHTPDA)と2-テノイルトリフルオロアセトン(Htta)を用いてY,Eu及びアクチノイドの協同抽出を行い,抽出錯体の化学形を調べた。試薬濃度が一定の条件下で(すなわちY,Cm,Cfについては0.748mM[DMDHOPDA]及び5mM[Htta],Uについては2.8mM[DMDHOPDA]及び0.5mM[Htta],溶媒はトルエンを使用した)log DとpHのプロットが曲線関係を示した。更にlog Httaとlog D及びlog DMDHOPDAとlog D関係の結果を併せて解析して,M(DA)2(tta)(X)2やM(DA)(tta)2(X)(ここでM:Cm,Cf;DA:DMDHOPDA;X-:ClO4-)など2種以上の抽出錯体を見いだした。更に,DMDHTPDAとHttaの協同抽出において,Eu,Am,Th,及びUをニトロベンゼンに抽出する際にも,複数の錯体が生成することを確認した。

Using a wet-chemical method based on flow-coulometry, an analytical method to measure unstable ions of copper, CuO + and Cu + , in superconductors has been advanced. The distributions of these ions from the surface to inside of sample discs were determined by the developed method. The sample discs, which were prepared by the ceramic method, contained a lower CuO + /Cu total ratio at the outermost surface, and gradually increased to a depth of 200 μm. On the contrary, the Cu + /Cu total ratio in a YBa 2 Cu 3 O 6 sample was almost homogeneous. The positively electrolyzed La 2 CuO x disc as an electrode exhibited a much higher oxidation state than that without electrolysis. It was confirmed that the CuO + /Cu total ratio on the surface and in the bulk of the electrolyzed La 2 CuO x had an influence on the superconducting characteristics.

The application of gas deposition method (GDM) to the formation of 3d transition metal nano-crystals and their structure is reported. A He circulation system was installed in order to purify the inert gas used during the preparation. The metals of Fe, Co, and Ni were evaporated by RF heating using a ZrO2 linear set in a tungsten crucible and a carbon crucible. X-ray diffraction study reveals the same crystal structure as those of bulk states for Fe and Ni (bcc and fcc), while the Co nanocrystal has modified structure from the fcc structure. The averaged grain sizes are ranged about 5 nm. The magnetization are more than 95 % of bulk except for samples with loose packing, which were prepared with lower pressure difference between the evaporation and deposition chambers. It is found that oxidization is remarkably suppressed during the fabrication process.

The diamide, N,N′-dimethyl-N,N′-dihexyl-3-thiopentanediamide (DMDHTPDA) was synthesized and thested for extraction of Eu(III), Am(III), Th(IV) and U(VI). DMDHTPDA shows a very weak complexation with these metal ions, which can be attributed to the soft base nature of the sulfur atom. None of the cations were extracted into the organic phase when DMDHTPDA alone was present. Synergistic extraction was measured for DMDHTPDA plus thenoyltrifluoroacetone. From the extraction dependencies on pH and extractant concentration, formation of mixed TTA+DMDHTPDA complexes were indicated. Except for the Th(IV) system, the separation and synergistic factors were smaller for the TTA+DMDHTPDA extractant than for the system of TTA+DMDHOPDA (the oxo ether analog of DMDHTPDA).

We investigate the surface morphology of nanocrystalline Au (n-Au) specimens prepared by a gas deposition (GD) method as well as the effect of 20 MeV proton irradiation at 1.5 K on the elastic properties of the n-Au specimen. It is suggested that small clusters of 10–20 ultrafine particles are simultaneously formed during the formation of the ultrafine particles above the Au melt. The large decreases in the low-temperature Young's modulus ( ΔE ) after proton irradiation are found, where ( ΔE/E )/C FP is 10 to 10 2 times larger than those reported for bulk metals ( C FP , concentration of Frenkel-pairs). We give a brief statement for this reasoning that such a large (ΔE/E)/C FP reflects a diaelasticity associated with some modifications of the grain boundaries owing to irradiation-induced defects.

The diamide type extractants (N, N′-dimethyl-N, N′-dihexyl-3-oxapentanediamide, DMDHOPDA, N, N′-dihexyl-3-thiopentanediamide, DHTPDA, and N, N′-dihexyl-3-oxapentanediamide, DHOPDA) were synthesized and tested for the extraction of the lanthanide and actinide elements. The elements, Eu3+, Am3+, Th4+, NpO2+ and UO22+, when extracted by DMDHOPDA, showed no pH-dependence. The relationships between log[DMDHOPDA] and log D under different ionic strengths were investigated in order to clarify the extraction reactions. The separation factor for Eu3+/Am3+ is 8.64.

The novel wet-chemical method for the analysis of the concentration and the distribution of constituent(s) at a higher oxidation state, [CuO] + , in superconducting La 2− x Sr x CuO y was developed. The sample pellet was dissolved in a flow of acid solution containing Fe 2+ , and the solution was introduced continuously into a flow-coulometric system composed of two-step column electrodes of glassy carbon fibers as working electrodes. Fe 3+ generated in the solution through the stoichiometric redox between [CuO] + and Fe 2+ was detected at the first column electrode, and Cu 2+ in the dissolving solution was detected at the second column. It was obvious that the [CuO] + concentration in the surface region of ca. 200 μm in depth from the surface was lower than that of the bulk pellet and the distribution of [CuO] + near the surface was dependent on such sample-preparation parameters as sintering time, annealing atmosphere and storage time of the pellets, etc.

A new method for the determination of (CuO)+/Cutotal in the superconducting La2-XSrXCuOy was developed, which is based on the continuous dissolution of the sample pellet in a flowing solution of Fe2+, and the flow-coulometric detections of Fe3+ generated through the stoichiometric redox reaction of (CuO)+ with Fe2+ and the total Cu2+ dissolved. The (CuO)+/Cutotal ratio down to 0.0003 in the bulk of the sample as well as the distribution of the ratio from surface to inside of the pellet can be determined.

The Refracted X-ray Fluorescence (RXF) method can obtain the information about surfaces and interfaces: for example, surface electron density, chemical condition and surface roughness. We evaluated surfaces and interfaces of ultrathin films by using RXF method, and we measured the average lattice constant of a ultrathin GaAs film, the top-layer of a GaAs substrate and the surface roughness of the Si substrate below a ultrathin GaAs film grown by MBE.

The overall feature of the reduction-oxidation behavior of U, Np or Pu ions in acidic aqueous solutions was investigated by flow-coulometry with multi-step column electrodes. Redox potentials, number of electrons involved in the electrode processes, and reversibilities of the processes were determined and the species participating in the reactions were discussed. Methods for the rapid preparation of the ion of a desired oxidation state and for the determination and the speciation of ions were developed.

Separation method of a few ppb of uranium and thorium in tantalum metal by ion exchange for neutron activation analysis was established. After dissolving tantalum metal by hydrofluoric acid, uranium and thorium were separated from tantalum using cation exchange resin column in 0.5M hydrofluoric −0.65M boric acid media. Both of the yields for uranium and thorium during separation were above 95% and the remaining amount of tantalum be lowered below 400 ng.

Fe nanocrystalline films were prepared by the gas-deposition method (GDM). The films were composed of small particles and their aggregates. With an increase of pressure difference between an evaporation chamber and a deposition chamber, the grain size is slightly reduced and lower coercivity is realized. The Mossbauer spectra consisted of a crystalline component (α-Fe) and a boundary component with a hyperfine field of 310 kOe; no oxide subspectrum was observed. Magnetizations of the samples are around 95% of that of bulk α-Fe. Fe nanocrystals prepared by GDM are found to show good oxidization resistance.

The magnetic properties and structures of Ni and NiFe nanocrystalline films prepared with the gas-deposition method (GDM) are investigated. From the results of STM and SEM, fine particles, approximately 10 nm in diameter, were seen in the films. Furthermore, aggregates several tens of nm in diameter, composed of the small particles, are also observed. The magnetization of the Ni nanocrystalline films is about 50 emu/g, or 90% of that of bulk Ni. Coercivity of the Ni nanocrystals ranged from 4 to 20 Oe. In the case of NiFe, the concentration of Fe is slightly increased as the evaporation temperature is increased.

The separation of Am and Cm from Sm, Eu, and Gd was examined by the combination of new extractant, DOODA (N,N,N′,N′-tetraoctyl-3,6-dioxaoctanediamide) and masking agent, TEDGA (N,N,N′,N′-tetraethyl...

A new technique for the back-extraction using photoreduction by the fourth harmonic of Nd:YAG laser has been successfully demonstrated in a liquid–liquid extraction system composed of a 1-octanol s...

Calorimetric investigation on the effect of enantiomeric excess on the smectic- (Sm ) – smectic-C* (SmC*) phase transition has been carried out using a high-sensitivity differential scanning calorimetry in an antiferroelectric liquid crystal compound. For highly optically pure samples, the Sm – SmC* transition is found to be first-order accompanying a thermal hysteresis, while the decrease in the optical purity weakens the first-order nature of the transition and eventually moves towards continuous behavior through the critical point. Our results indicate that the enantiomeric excess dramatically influences the nature of the Sm – SmC* transition.

Refraction effect of x-ray fluorescence, which can be measured with scattered x-ray fluorescence and take off angle distribution curve, was utilized to study surfaces and interfaces. Informations on island state of films, surface roughness, chemical state of thin films and so forth on optical flat substrate could be obtained.

A sensitive method for the determination of ruthenium involving the formation of volatile species in solution and subsequent nebulization for inductively coupled plasma/atomic emission spectrometry is proposed. The sensitivity of the determination of ruthenium was increased by a factor of 70 with the addition of 1×10 −2 M periodic acid as an oxidizing agent. The detection limit was 5 ng ml −1 of ruthenium and the calibration was linear over the range 0.01–0.5 μg ml −1 of ruthenium. Serious interferences were not found except from reducing agents.