Influence of the physico-chemical properties of Selangor soil series on the distribution coefficient (<Emphasis Type="Italic">K</Emphasis><Subscript>d</Subscript>-value) of <Superscript>226</Superscript>Ra

²²⁶Ra is a member of the ²³⁸U natural decay series and is one of the most important isotope to be determined among the naturally occurring nuclides in environmental samples. In order to evaluate the radiation dose from ²²⁶Ra, it is important to know its mobility in different types of soils. The aim of the present study is to quantify the influence of physico-chemical soil properties on ²²⁶Ra adsorption. The distribution coefficients (K _d-value) of ²²⁶Ra in Selangor soil series samples were measured in one core, at three depth levels to evaluate the adsorbability of ²²⁶Ra. The soil samples were spiked with ²²⁶Ra tracer and the activities of ²²⁶Ra in the separated phase from batch sorption test were measured by a low background but high efficiency well-type HPGe detector. Several physico-chemical soil properties were also characterised for each soil samples. Pearson’s correlation and stepwise multiple regression test were applied at the 0.05 level of significance throughout all analysis to determine the relationships and influences between distribution coefficients (K _d-value) of ²²⁶Ra with physicochemical soil properties for the Selangor soil series. The observed K _d value was in the range of 50.55–172.28 mL g⁻¹ (mean: 93.20 ± 46.99 mL g⁻¹). The regression showed that the highest positive correlations were observed for organic matter (OM) and cation exchange capacity (CEC) (r = 0.96**, 0.81**, respectively) with K _d-values. The results indicate that the stepwise multiple regression model incorporating the soil’s OM and CEC accounts for 98% of the variability in distribution coefficients of ²²⁶Ra.     

Determination of radium isotopes in soil samples by alpha-spectrometry

A sensitive and accurate method for determination of radium isotopes in soil samples by α-spectrometry has been developed ²²⁵Ra, which is in equilibrium with its mother ²²⁹Th, was used as a yield tracer. Radium in soil samples was fused together with Na₂CO₃ and Na₂O₂ at 600 °C, leached with HNO₃, HCl and HF, preconcentrated by coprecipitation with BaSO₄, separated from uranium, thorium and iron using a Microthene-TOPO chromatographic column, isolated from barium in a cation-exchange resin column using 0.05M 1,2-cyclohexylene-dinitrilo-tetraacetic acid monohydrate as an eluant, electrodeposited on a stainless steel disc, and counted by α-spectrometry. The detection limit of the method is 0.43 Bq·kg⁻¹ for ²²⁶Ra, ²²⁸Ra and ²²⁴Ra if 0.50 g of soil sample are analyzed. The method was checked with two certified reference materials supplied by the IAEA, and reliable results were obtained Fourteen soil samples collected from the refractory industry in Italy were also analyzed. The mean radiochemical yields for radium were 85.7±4.3%, and the obtained radium concentrations in the soil samples were in the range of 8.08–3878 Bq·kg⁻¹ for ²²⁶Ra, of 1.60–678 Bq·kg⁻¹ for ²²⁸Ra and 1.25–550 Bq·kg⁻¹ for ²²⁴Ra, with ²²⁸Ra/²²⁶Ra and ²²⁴Ra/²²⁶Ra ratios ranged from 0.159–0.821 and from 0.142 to 0.525, respectively.     

Coprecipitation of radium with calcium and strontium from acid solutions using crown ether and tungstosilicic acid

The coprecipitation of radium with strontium or calcium, 18C6 and tungstosilicic acid was studied. It was determined that radium is coprecipitated with Ca and Sr and mixed compounds are fomed. It was also find the yield of Ra depends on the ratio of stability constants of metals present in a solution with 18C6. The stability constant of Ra with 18C6 was determined using a precipitation method.     

Precipitation Behavior of Metal Ions in the Preparation of YBa2Cu3Oy and (Bi,Pb)2(Sr,Ca)4Cu3Oy Superconductive Materials in 8-Hydroxyquinoline-diethylamine Media

To prepare the YBa₂Cu₃O_y (Y-123) and (Bi, Pb)₂(Sr, Ca)₄Cu₃O_y (Bi-2223) superconductive materials, coprecipitation was used with 8-hydroxyquinoline (oxine) as precipitant to ensure complete precipitation. Various aspects of competitive reactions such as dissociation, precipitation, complex formation and association in the aqueous solution system containing metal ions, oxinate ion and diethylamine species have been explored in order to discover the optimal coprecipitation conditions of the title system. Experiments were conducted to confirm these conditions.     

Cesium, strontium, europium(III) and plutonium(IV) complexes with humic acid in solution and on montmorillonite surface

The effect of Aldrich humic acid (HA) on the mobility of¹³⁷Cs,⁸⁵Sr,¹⁵²Eu and²³⁹Pu radionuclides was studied in Ca-montmorillonite suspensions. Verified 2-sites-2-species (2s2s) models correspond to an intensive interaction of all elements with humificated surface, what is in a remarkable contrast with the weak complexation of cesium and even strontium in solutions — the neutral ligand interaction constants β (l/mol) are log β<−9.9 and 7.56±0.21 for Cs and Sr, respectively. The result for europium complexation in solution, log β=12.49±0.18 is in a good agreement with literature data. For plutonium(IV) not only a high proton competitive constant in solution was obtained, log β β=(−0.67±0.32)+3pH, but also a strong chemisorption, which at high concentrations of humic acid (above 0.05 g/l) indicates the formation of bridge humate complexes of plutonium on the humificated surface. Logarithms of heterogeneous interaction constants ( ₂₄ l/g) of the elements with surface humic acid are 4.47±0.23, 4.39±0.08, and 6.40±0.33 for Cs, Sr, and Eu(III), respectively, and the logarithm of the proton competitive constant ( ₂₄, l/g) for Pu(IV) −3.80±0.72. Distribution coefficients of humic acid and metal humates between 0.01 g HA/l solution and montmorillonite were derived as logK _d(AH)=−1.04±0.11, logK _d(EuA)=1.56±0.11 and logK _d(PuA)=2.25±0.04, while the values for Cs and Sr were obtained with very high uncertainty. Speciation of the elements on montmorillonite surface is illustrated as a function of equilibrium concentration of humic acid in solution and of pH.     

Conductivity Studies of <Emphasis Type="Italic">n</Emphasis>-Tetrabutylammonium Tetraphenylborate in 3-Pentanone in the Temperature Range from 283.15 to 329.15 K

The molar conductivities (Λ) of solutions of n-tetrabutylammonium tetraphenylborate (NBu₄BPh₄) in 3-pentanone have been measured in the temperature range from 283.15 to 329.15 K. The conductance data have been analyzed using the Lee-Wheaton conductivity equation with the distance parameter (a) set at Bjerrum’s pairing distance, and the limiting molar conductivities (Λ_o) and the association equilibrium constants (K _A) have been derived. The limiting ion conductivities (λ_±^o) have been evaluated according to the method of Krumgalz. The λ₊ ^o values have been compared with λ₊ ^o values calculated from the empirical equation of Gill. The thermodynamic functions, Gibbs energy (Δ G _A ^o), enthalpy (Δ H _A ^o) and entropy (Δ S _A ^o) for the process of ion-pair formation as well as the activation energy of the ionic movement (ΔH ^∗) have been evaluated. The obtained results are discussed in terms of ion-ion and ion-solvent interactions.     

A simple radiochemical method for determining bone-seeking radionuclides in bone and teeth: 90Sr in teeth of children from Ukraine and Germany

Bone is a critical organ for the accumulation of ⁹⁰Sr but also of other “bone-seeking” radionuclides such as Ra, Pb, Th, U and Pu. That's why a simple radiochemical procedure to separate ⁹⁰Sr, ²¹⁰Pb, ²²⁶Ra, Th_nat. U_nat., ²³⁸Pu and ^239/240Pu from bone and teeth was developed. The separation scheme is based on extraction chromatography. Deciduous teeth, extracted from children born in 1982-1991 were collected in various regions of Germany and in Northwest Ukraine and analyzed for ⁹⁰Sr concentrations with regard to the Chernobyl accident in 1986. The teeth were grouped into samples according to the year of birth and the residence of the donors. The ⁹⁰Sr content in teeth from the Ukraine (mean = 63.8 mBq/g Ca) averaged more than twice as much as that found in teeth from Germany (mean = 28.4 mBq/g Ca). The obvious explanation for this effect is that the concentration of ⁹⁰Sr decreased with increasing distance from the damaged Chernobyl nuclear power plant. The measured levels of ⁹⁰Sr concentrations, however, were much lower than ⁹⁰Sr concentrations determined in the mid-60s and mid-70s. This revised version was published online in July 2006 with corrections to the Cover Date.     

Multicolour models of natural embedding for SU(2≥m≥4)×S 10↓D 5 NMR spin symmetry: Determinacy of nuclear spin weights for (1,12)-car-11B-boranes

The inherent (in)determinacy implicit in the SU(m≥3)×S _n↓G natural embedding aspects of (NMR) spin symmetry of clusters is investigated, as part of a multicolour modelling scheme, where the SU2-branching level meets the initial n(S _n)=/G/ condition. We focus on correlative mappings derived from [λ]_SA (self-associate) irreps for natural group embeddings and compare these with certain Yamanouchi-Gel'fand chain properties of S ₁₀ Mathematical decompositions of M^λ simple S _n-modules with (2≥p≥4)-branchings of λ⊵,λ_SA (for λ⊢N partitions of _n) provide the initial insight into the monocluster spin (NP) physics of [²H_]10, [¹¹B]₁₀ (S ₁₀↓D ₅), as aspects of (1,12)-(HC)₂(¹¹B)₁₀ or (HC)₂(^{2 11}B₁₀ carborane cage isotopomers. The questions raised are significant for their impact on CNP nuclear spin weighting of ro-vibrational spectra. The methods used are those of combinatorics-via-group actions, as physical S _n-encodings applied to nuclear spin algebras. This revised version was published online in July 2006 with corrections to the Cover Date.     

Note on the Coulson integral formula

Let P be a polynomial of degree n, whose zeros λ₁, λ₂, ..., λ _n are real-valued. The Coulson integral formula (first reported in 1940) is an expression for the sum of the positive–valued zeros of P, in terms of P. We show that the Coulson formula holds if and only if the condition λ₁+λ₂+...+λ _n =0 is obeyed. We also show how the formula has to be modified, so that it be applicable in the case when λ₁+λ₂+...+λ _n ≠ 0. Ams Classification (2000): primary: 92E10, secondary: 32A27, 81Q99     

Cyclopalladated complexes of 2-phenylbenzothiazole with 4,4′-bipyridyl

Complexes [Pd(bt)(4,4′-bpy)OOCCH₃], [Pd(bt)NO₃]₂(m-4,4′-bpy), [Pd(bt)(m-4,4′-bpy)]₄(NO₃)₄ (bt⁻ is deprotonated form of 2-phenylbenzothiazole, bpy is 4,4′-bipyridyl) are prepared and characterized by ¹H NMR, electron absorption and emission spectroscopy, as well as by voltammetry. The upfield shift of the signal of proton in the ortho-position to the donor carbon atom of the cyclopalladated ligand in the complexes [(Δδ = −(1.1–1.5) ppm] is assigned to the anisotropic effect of the ring current of the pyridine rings of the 4,4′-bipyridyl moiety, which are orthogonal to the coordination plane. Characteristic longwave absorption bands λ = (387±4) nm and the low-temperature phosphorescence bands λ = (512±3) nm in the complexes are assigned to the chromophore {Pd(bt)} metal complex fragment. The reduction waves in the complexes [E _1/2 = −(1.54±0.04) and E _p = −(1.83±0.03) V] are assigned to the ligand-centered processes of the successive electron transfer to the π* orbitals localized predominantly on the coordinated pyridine components of the 4,4′-bipyridyl moiety.     

Enantioselective liquid-solid extraction for screening of structurally related chiral stationary phases

Summary An enantioselective liquid-solid batch extraction method is described for the screening of novel chiral stationary phases (CSPs) during optimization studies of chiral selectors derived form a common lead structure. Extraction enantioselectivity (α) values can be calculated from the enantiomeric excess ee-values of the selectand, which are measured in the liquid phase by enantioselective HPLC. Extraction α-values have been correlated with chromatographic α-values. The influence was studied of several experimental parameters of the assay (pH_a, buffer concentration, temperature, selector/selectand and phase ratio) on the enantiomeric excess (ee) values of the selectands and the enantioselectivity of the CSPs, respectively. The derived statistically significant model has then been implemented to predict chromatographic α-values of novel CSPs. For example, an ee of 89.3% for DNB-Leu as selectand could be achieved in batch extraction for a novel synthesized but mechanistically similarly-acting CSP derived form quinine. This corresponds to a calculated extraction α-value of 17.7. Based on this α_extraction a chromatographic α-value of 28.8 was predicted by the linear correlation model; the experimental HPLC α-value of 31.7 was in good agreement and demonstrated the validity of the proposed screening method. The method is particularly helpful in SO optimization studies.     

Characterization and catalytic behavior of La2 - x (Sr, Th)xCuO4 ± λ in reaction NO+CO

Two mixed oxide systems La₂-_xSr_xCuO_{4± λ} (0.0⩽x⩽1. 0) and La_2-xTh_xCuO_{4± λ} (O. O⩽x⩽ 0.4) with K₂NiF₄ structure were prepared by varyingx values. Their crystal structures were studied by means of XRD and IR spectra. The average valence of Cu ion at B site, nonstoichiometric oxygen (λ) and the chemical composition in the bulk and on the surface of the catalysts were measured by means of chemical analysis and XPS. The catalytic behavior in reaction CO+NO was investigated under the regular change of average valence of Cu ion at B site and nonstoichiometric oxygen (λ). Meanwhile, the adsorption and activation of the small molecules NO and the mixture of NO+CO over the mixed oxide catalysts were studied by means of MS-TPD. The catalytic mechanism of reaction NO+CO over these oxide catalysts were proposed; and it has been found that, at lower temperatures the activation of NO is the rate determining step and the catalytic activity is related to the lower valent metallic ion and its concentration, while at higher temperatures the adsorption of NO is the rate determining step and the catalytic activity is related to the oxygen vacancy and its concentration. Project supported by the National Natural Science Foundation of China.     

The mechanosorption of carbon dioxide by magnesium, calcium, and strontium metasilicates

Processes that occurred in the mechanical activation of MSiO₃ silicates (M = Mg, Ca, Sr) in a centrifugal planetary mill in the atmosphere of carbon dioxide (p(CO₂) = 10⁵ Pa) were comparatively studied. The interaction of carbon dioxide with silicates had the character of deep mechanosorption with massed penetration of gas molecules into the volume of particles and their “solution” in structurally disordered silicate matrices in the form of distorted CO₃²⁻ ions. No individual carbonate phases were formed. The absorbing ability of silicates with respect to carbon dioxide decreased in the series SrSiO₃ > CaSiO₃ > MgSiO₃. The carbon dioxide mechanosorption coefficients K _MS were calculated for Mg, Ca, and Sr silicates according to the earlier suggested kinetic model. A linear dependence of logK _MS on Δ_r G ₂₉₈^o for the transformation of silicates into the corresponding carbonates was observed.     

Probability of fluctuations of the number of nearest neighbors in a hard sphere liquid: Asymptotic decomposition

Fluctuations of the number of nearest neighbors M _λ inside the coordination sphere of a given radius λ, in a hard sphere liquid (M _λ is the total number of neighbors for all N particles of the system) are analyzed. For the probability density distribution of this random value, an exact asymptotic decomposition over the number of particles N in the system has been derived, and the decomposition coefficients were recorded in terms of the semi-invariants of the random value of Mλ The result coincides completely with the asymptotic decomposition in the central limiting theorem of the probability theory. Due to this, the number of nearest neighbors in a liquid of N hard spheres can be represented as the sum of N independent random values with equal distributions. The hard sphere liquid of N particles was simulated by the Monte Carlo method in the canonical Gibbs ensemble over a wide range of densities (N= 864, periodic boundary conditions, occupancy pg from 0.005 to 0.500). The theoretical equations are in good agreement with the results of simulation.     

Electrical Conductance Studies in Aqueous Solutions of Glutaric Acid,Disodium Glutarate and Sodium Hydrogen Glutarate

Conductivity measurements of glutaric acid and disodium glutarate in dilute aqueous solutions were performed in the 288.15 to 323.15 K temperature range. The limiting equivalent conductances of glutarate anions, λ ^o(HGlut⁻,T) and λ ^o(1/2Glut²⁻,T), and the dissociation constants of glutaric acid, K ₁(T) and K ₂(T), were derived by the use of the Onsager and the Quint and Viallard conductivity equations. The applied molecular model was successfully confirmed by analyzing the conductivities of sodium hydrogen glutarate at 298.15 K.     

Application of ICP-QMS for the determination of ultratrace-levels of <Superscript>226</Superscript>Ra in geothermal water and sediment samples

A rapid, accurate and less labor intensive approach to determining ²²⁶Ra in environmental samples was examined; this utilized quadrupole-based inductively coupled plasma mass spectrometry (ICP-QMS). The procedure used chemical separation by ion exchange chromatography to remove most of the matrices after coprecipitation with BaSO₄. The average chemical recovery of the NIST SRM preparation method ranged from 60.5 to 85.9% using ¹³³Ba as internal tracer by gamma counting. This technique was capable of completing a ²²⁶Ra measurement within 3 min. It did not require an in-growth period to allow radon and its progeny to achieve secular equilibrium with the parent ²²⁶Ra as is needed for liquid scintillation analyzer (LSA). The method detection limits for the determination of ²²⁶Ra in geothermal water and sediment samples were 0.02 mBq L⁻¹ (0.558 fg L⁻¹) and 0.10 Bq kg⁻¹ (2.79 fg g⁻¹), respectively. The results obtained with various natural samples and the suitability of the method when applied to various environmental matrices such as geothermal water and sediment are discussed. When ICP-QMS was compared to double-focusing magnetic sector field inductively coupled plasma mass spectrometry (ICP-SFMS), good agreement was obtained with a correlation coefficient, r ² = 0.982.     

The Solubility of Boric Acid in Electrolyte Solutions

The solubility of boric acid [B] in LiCl, NaCl, KCl, RbCl, and CsCl was determined as a function of ionic strength (0–6 mol ⋅ kg⁻¹) at 25 ^∘C. The results were examined using the Pitzer equation

Transfer of 226Ra, 85Sr and 137Cs from milk to milk products</p> </p>

Summary Transfer of ²²⁶Ra, ⁸⁵Sr and ¹³⁷Cs from cow and sheep milk to various Syrian dairy products has been evaluated. Dairy products include Kashkivan cheese, braided cheese, Haloom cheese, Sircassian cheese, liquid cheese, native cheese, cottage, thick yogurt, butter and milk cream. The results showed that the percentage of ²²⁶Ra, ⁸⁵Sr and ¹³⁷Cs transferred from cow milk to milk cream (P_t=food processing retention factor′processing efficiency′100%) has reached 32%, 16% and 7%, respectively. Butter and liquid cheese were found to have the lowest percentage of transferred 226Ra, ⁸⁵Sr and ¹³⁷Cs. Most of the obtained P_t values of the studied radionuclides in thick yogurt were relatively low in spite of the high processing efficiencies of thick yogurt. Moreover, the transfer, P_t, of the studied radionuclides from cow milk to the prepared cheese was higher than those values determined for sheep milk. This is due to differences in chemical compositions of each type of milk. On the other hand, the treatment of Native cheese, most commonly consumed cheese in Syria, with different concentrations of NaCl solutions showed that ¹³⁷Cs was completely removed from cheese soaking in 5% NaCl solution (soaking time of 48 hours), while 40% of ²²⁶Ra and 80% of ⁸⁵Sr were also decontaminated using 0-2.5% NaCl solutions and soaking time of 48 hours. Based on the obtained results, industrialization processes of the dairy products that resulted the removal of radionuclides have been identified.</p> </p>     

Determination of the Active Metabolite of Prulifloxacin in Human Plasma by HPLC with Fluorescence Detection

A cheap, simple and rapid sample preparation method has been developed for quantification of ulifloxacin, the active metabolite of prulifloxacin in human plasma, by HPLC with fluorescence detection using lemefloxacin as the internal standard. One-step protein precipitation with 10% perchloric acid (2:1, v/v) on a 200 μL sample was used. The separation was performed at 30 °C on a C18 column using an eluent of acetonitrile-0.5% triethylamine buffer. The compounds were monitored at λ _ex of 280 nm, λ _em of 425 nm. The calibration curve for ulifloxacin in human plasma was linear over the range 0.01–1.00 μg mL⁻¹. The lower limit of quantification is 0.01 μg mL⁻¹. The intra- and inter-day precision ranged from 3.0 to 6.7%, respectively. The method had been used for clinical pharmacokinetic studies of prulifloxacin formulation product after oral administration to healthy volunteers. Jun Wen and Zhenyu Zhu have equal contribution to this work.