Rapid determination of 239,240Pu, 238Pu, 241Am and 90Sr in high contaminated samples waste using combined SPE sorbents AnaLig® Pu-02, AnaLig® Sr-01 and DGA® Resin

A rapid separation method has been developed which allows measurement of plutonium, americium and strontium isotopes in the high active sample from CBRN Training and Testing Centre in Zemianske Kostolany (Slovakia) with high chemical recoveries and effective removal of matrix interferences. This method uses different commercial products stacked AnaLig^® Pu-02, AnaLig^® Sr-01 and DGA^® Resin cartridges from IBC Advanced Technologies and Eichrom Technologies. The method allows rapid separation of plutonium, strontium and americium using a single multi-stage column in the vacuum box (cartridge technology) with rapid flow rates to minimize sample separation time. The ^239,240Pu, ²³⁸Pu and ²⁴¹Am were determined by alpha spectroscopy, ⁹⁰Sr was counted on TRICARB 2900 TR by Cerenkov counting of its progeny ⁹⁰Y.     

Determination of 239,240Pu, 238Pu isotopes in soil samples using molecular recognition technology product AnaLig?Pu-02 gel

Procedure for analysis of plutonium isotopes in soil samples was developed using a new molecular recognition technology product AnaLig^?Pu-02 gel. Extraction chromatography TEVA^? Resin was used for purification of plutonium phase to remove thorium impurities which interfere in Pu determination by alpha spectrometry. The performance of the method was successfully tested by analysis of a sand stimulant sample and a soil sample spiked with known activity of ²³⁹Pu. The results obtained for procedures were compared in terms of activities and recoveries.     

Statistical suitability testing of the Aliquat-336, AnaLig® Pu-02 and TRU® Resin use for the 239,240Pu, 238Pu determination

In this paper three different methods were used for plutonium separation and statistical tested-molecular recognition technology products AnaLig^® Pu-02, liquid–liquid extraction with Aliquat-336 and extraction chromatography with TRU^® Resin. The methods performance was investigated by analysis of NPL (High Alpha–Beta 2005) intercomparison sample. Regression diagnostics procedures were used for examination of the regression triplet and pair t test were applied for comparison of methods for the separation of ^239,240Pu, ²³⁸Pu with Aliquat-336, TRU^® Resin and AnaLig^® Pu-02. The presented results were evaluated as correct for all experimental data.     

Statistical suitability testing of 3M Empore™ Sr disc and AnaLig® Sr-01 use for 90Sr determination

In this paper rapid separation methods for strontium determination using molecular recognition technology products 3M Empore? Sr disc, AnaLig^® Sr-01 and extraction chromatography Sr^® Resin were presented and statistical tested. The methods performance was investigated by analysis of NPL (High Alpha–Beta 2003) and (High Alpha–Beta 2005) intercomparison samples. The presented results were evaluated as correct for all experimental data. We used linear regression (with regression diagnostics), t test and the mean of variable using ⁹⁰Sr with 3M Empore? Sr disc, AnaLig^® Sr-01 and Sr^® Resin.     

A comparison of classical 90Sr separation methods with selective separation using molecular recognition technology products AnaLig? SR-01 gel, 3M Empore? Strontium Rad Disk and extraction chromatography Sr?Resin

We studied the use of an extraction chromatography for determination of ⁹⁰Sr in contaminated water samples. The aim of our work was to compare selected products from the point of view of the strontium chemical yields and analysis time. Three commercial products, 3M Empore? Strontium Rad Disk, AnaLig^® Sr-01 gel, Sr^®Resin, and two classical methods, liquid?Cliquid extraction with tributhylphosphate and carbonate co-precipitation, were tested for the separation of ⁹⁰Sr. The water sample from nuclear power plant A1 Jaslovske Bohunice was used for radiochemical analysis of ⁹⁰Sr volume activity. Samples were traced with ⁸⁵Sr to monitor strontium chemical recovery and counted either by Cerenkov counting on TRI CARB 2900 TR liquid scintillation counter or low level alpha?Cbeta proportional counter.     

Contents of238Pu,239,240Pu and137Cs in sediments and shore depositions of the Vltava river in 1995–1996

The²³⁸Pu,^239,240Pu and¹³⁷Cs concentrations in sediments and shore deposition samples of the Vltava river were determined.^239,240Pu and¹³⁷Cs concentrations in sediment samples (five locations) ranged from 19.6 to 124.8 mBq·kg⁻¹ and from 1.8 to 28.2 Bq·kg⁻¹, respectively. The²³⁸Pu,^239,240Pu and¹³⁷Cs concentrations in shore deposition samples (four locations) ranged from 2 to 16.8, from 26.8 to 477.2 mBq·kg⁻¹, and from 1.6 to 86.3 Bq·kg⁻¹, respectively. The superficial activity of studied radionuclides in shore deposition areas was determined and radionuclide origin at studied locations was discussed.     

Spectra and dose with ANN of 252Cf, 241Am–Be, and 239Pu–Be

Artificial neural networks have been applied to unfold the neutron spectra and to calculate the effective dose, the ambient equivalent dose, and the personal dose equivalent for ²⁵²Cf, ²⁴¹Am–Be, and ²³⁹Pu–Be neutron sources. The count rates that these neutron sources produce in a Bonner Sphere Spectrometer with a ⁶LiI(Eu) were utilized as input in both artificial neural networks. Spectra and the ambient dose equivalent were also obtained with BUNKIUT code and the UTA4 response matrix. With both procedures spectra and ambient dose equivalent agrees in less than 10%. The Artificial neural network technology is an alternative procedure to unfold neutron spectra and to perform neutron dosimetry.     

Structure and Luminescence Characteristics of Europium Activated Strontium Silicates Sr（Eu ,Bi）SiO3 and Sr（Eu ,Bi）2SiO4

Sr2SiO4 ： Eu^3 , Bi^3 and SrSiO3 ：Eu^3 , Bi^3 samples were synthesized at high temperature and high pressure. The effect of high pressure on the structure and luminescence properties of the samples were stud-ied. As a comparison, the samples were also prepared by the method of sol-gel at high temperature and atmo-spheric pressure. The SrSiO3 ： Eu^3 , Bi^3 prepared at atmosphere has a hexagonal phase structure; in the pressure range of 2. 34—4. 10 GPa, it is transformed into a pseudo-orthorhombic structure (monoclinic), and in the pressure range of 4. 10—4. 15 GPa, the structure change of Sr2SiO4 ： Eu^3 , Bi^3 has not been ob-served, it maintains the monoclinic structure of the samples synthesized at an atmospheric pressure. High pressure makes the luminescence properties of the samples changed obviously. The intensity and the relative quantum luminescent efficiency decrease, the half-width increases obviously and the red shift occurs. The changes of the luminescence properties result from the pressure-induced changes of the crystal structures.     

Crystal Structure of (Hg, Ce, Cu)(Sr, Pr)2(Pr, Sr)Cu2O6+δ and (Hg, \square )(Sr, Pr)2(Pr, Sr)2Cu3O8+δ Phases

This paper reports on the refined compositions and crystal structures of two phases from the homologous series (Hg, M)(Sr, Pr)₂(Pr, Sr)_k-1Cu_kO_2k+2+ with k = 2 (Hg-1212) — (Hg_0.44(2)Ce _0.31 ⁴⁺ Cu_0.25)(Sr_0.90(3)Pr_0.10)₂(Pr_0.52(3)Sr_0.48)Cu_2.00O_7.00 (a = 3.8634(1), c = 12.2030(8) , space group P4/mmm) with k = 3 (Hg-1223) — (Hg_0.29(1) )(Sr_0.67(2)Pr_0.33)₂(Pr_0.61(2)Sr_0.39)₂Cu_3.00O_9.32(8) or (Hg_0.29(1) )(Sr_0.61(4)Pr_0.39)₂(Pr_0.51(4)Sr_0.49)₂Cu_3.00O_9.00 (with a fixed content of superstoichiometric oxygen O(4) in the phase) ( is a vacancy; a = 3.8294(9), b = 3.8567(6), c = 15.2763(44) , space group Pmmm). The implausibly high content of oxygen in the Hg-1223 phase (refinement I) is attributed either to O–O bond formation or to the possible presence of a minor amount of copper in a defect position of Hg; the inclusion of the latter in structure refinement leads to a better reproduction of the real structure but increases the R indices. The crystal-chemical analysis of the title phases and a comparison with the available data for analogous phases indicates that the composition of the crystallographic positions is related to structural features, in particular, to the coordinates of (Hg, M) and superstoichiometric oxygen, whose content depends on the degree of substitution of strontium ions by praseodymium ions. Reasons for the orthorhombic distortion of the Hg-1223 phase are discussed. The absence of superconductivity is explained by the nonoptimal formal charge (FC) of copper, which depends on the oxygen content in the phase.     

Death,taxes, and the genetic code?

The genetic code is an enduring feature of biology: only rare circumstances result in changes to translation of the code, at least in nature. Researchers are devising methods to engineer ribosome-synthesized polypeptides containing novel and potentially useful amino acids.     

Contracted polarization functions for the atoms Ca, Ga–Kr, Sr, and In–Xe

 Contracted Gaussian-type function sets are proposed for polarization functions of the atoms Ga–Kr and In–Xe. We also report polarization functions for Ca and Sr. A segmented contraction scheme is used for its compactness and computational efficiency. The contraction coefficients and orbital exponents are fully optimized to minimize the deviation from accurate atomic natural orbitals. The present polarization functions yield more than 99% of atomic correlation energies predicted by accurate natural orbitals of the same size. Received: 23 February 2001 / Accepted: 19 April 2001 / Published online: 13 June 2001     

Investigations in the systems Sr–As–O–X (X = H,Cl): Preparation and crystal structure refinements of the anhydrous arsenates(V) Sr3(AsO4)2, Sr2As2O7, α- and β-SrAs2O6, and of the apatite-type phases Sr5(AsO4)3OH and Sr5(AsO4)3Cl

The previously uninvestigated atomic arrangements of six strontium arsenate(V) phases in the systems Sr-As-O-X (X = H, Cl) have been determined. Single crystals of Sr₃(AsO₄)₂ and Sr₅(AsO₄)₃Cl were grown from a borate and NaCl melt, respectively, whereas single crystals of α- and β-SrAs₂O₆ and of Sr₅-(AsO₄)₃OH were obtained under hydrothermal conditions. Microcrystalline samples of Sr₂As₂O₇ were prepared by solid-state reaction of As₂O₅ with SrCO₃ and, alternatively, by thermolysis of SrHAsO₄. Crystal structure determinations based on powder X-ray diffraction data using the Rietveld method (Sr₂As₂O₇), and from single-crystal X-ray diffraction data (all other phases) revealed isotypism with known structure types (except β-SrAs₂O₆ which represents a new structure type). Sr₃(AsO₄)₂ crystallizes in the K₂Pb(SO₄)₂ structure type; Sr₂As₂O₇ is isotypic with the high-temperature polymorphs of Ca₂P₂O₇ and Sr₂V₂O₇, but itself shows no polymorphism; Sr₅(AsO₄)₃OH and Sr₅(AsO₄)₃Cl crystallize with the hydroxylapatite and chloroapatite structure, respectively; SrAs₂O₆ is dimorphic. Like all other known M^IIAs₂O₆ metaarsenates (M = Mn, Co, Ni, Sr, Pd, Cd, Hg, Pb), the α-polymorph crystallizes in the PbSb₂O₆ structure type, whereas the novel β-polymorph is the first example of a M^IIAs₂O₆ superstructure with a doubled c-axis. Additional analytical methods using Raman spectroscopy and thermal analyses support the results of the X-ray structure work.     

Science and Arts,Philosophy and Science: Why after All? Why Not?

This perspective summarizes some interdisciplinary aspects of science and the relation to philosophy, also including the basic motivations and aims as they might be discussed with young scientists starting their careers and presented also in the form of a commencement speech. The contents of this speech were repeatedly discussed also with Jack Dunitz, who showed great interest in it, given his broad interests. The speech also referred to an earlier commencement speech by Jack Dunitz in 1989. In the introduction of our essay, we mention the early common history of science and humanities under the name of philosophy. This early history can be traced back to ancient Greek philosophy and the ‘academy’ of Platon in Athens with a history of more than 1000 years until closure in 529 AD, in modern times revived as the National Greek Academy in Athens in the 19th and 20th centuries. Other ‘academies’ in Europe started in the 17th century and had publications under various names involving ‘philosophy’ with a focus on what we call science (natural science) today. After about 1800 there was increasing fragmentation of the various fields of knowledge and philosophy was considered to be part of the modern ‘humanities’ quite separate from science, and the natural sciences were fragmented into physics, chemistry, biology etc., and even finer subdivisions. The essay also describes an effort at ETH Zurich, reintegrating the various subfields of science and also stressing an education of scientists and engineers in the humanities. The essay concludes with a discussion of several global risks for mankind and a scientific imperative to maintain life on Earth. The common aspects and the foundations of all sciences as fields of knowledge aiming for an understanding of the world around us and of human beings as part of it are discussed from various perspectives.     

Distance-of-Flight Mass Spectrometry: What,Why, and How?

Distance-of-flight mass spectrometry (DOFMS) separates ions of different mass-to-charge (m/z) by the distance they travel in a given time after acceleration. Like time-of-flight mass spectrometry (TOFMS), separation and mass assignment are based on ion velocity. However, DOFMS is not a variant of TOFMS; different methods of ion focusing and detection are used. In DOFMS, ions are driven orthogonally, at the detection time, onto an array of detectors parallel to the flight path. Through the independent detection of each m/z, DOFMS can provide both wider dynamic range and increased throughput for m/z of interest compared with conventional TOFMS. The iso-mass focusing and detection of ions is achieved by constant-momentum acceleration (CMA) and a linear-field ion mirror. Improved energy focus (including turn-around) is achieved in DOFMS, but the initial spatial dispersion of ions remains unchanged upon detection. Therefore, the point-source nature of surface ionization techniques could put them at an advantage for DOFMS. To date, three types of position-sensitive detectors have been used for DOFMS: a microchannel plate with a phosphorescent screen, a focal plane camera, and an IonCCD array; advances in detector technology will likely improve DOFMS figures-of-merit. In addition, the combination of CMA with TOF detection has provided improved resolution and duty factor over a narrow m/z range (compared with conventional, single-pass TOFMS). The unique characteristics of DOFMS can enable the intact collection of large biomolecules, clusters, and organisms. DOFMS might also play a key role in achieving the long-sought goal of simultaneous MS/MS.

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Densities, Specific Heat Capacities, Apparent and Partial Molar Volumes and Heat Capacities of Glycine in?Aqueous Solutions of Formamide, Acetamide, and?N,N-Dimethylacetamide at T=298.15?K and?Ambient Pressure

Apparent molar volumes (V _2,φ ) and heat capacities (C _p2,φ ) of glycine in known concentrations (1.0, 2.0, 4.0, 6.0, and 8.0 mol⋅kg⁻¹) of aqueous formamide (FM), acetamide (AM), and N,N-dimethylacetamide (DMA) solutions at T=298.15 K have been calculated from relative density and specific heat capacity measurements. These measurements were completed using a vibrating-tube flow densimeter and a Picker flow microcalorimeter, respectively. The concentration dependences of the apparent molar data have been used to calculate standard partial molar properties. The latter values have been combined with previously published standard partial molar volumes and heat capacities for glycine in water to calculate volumes and heat capacities associated with the transfer of glycine from water to the investigated aqueous amide solutions, D[`(V)]<sub>2,tr</sub><sup>o</sup>\Delta\overline{V}_{\mathrm{2,tr}}^{\mathrm{o}} and D[`(C)]_p2,tr^o\Delta\overline{C}_{p\mathrm{2,tr}}^{\mathrm{o}} respectively. Calculated values for D[`(V)]<sub>2,tr</sub><sup>o</sup>\Delta\overline{V}_{\mathrm{2,tr}}^{\mathrm{o}} and D[`(C)]_p2,tr^o\Delta\overline{C}_{p\mathrm{2,tr}}^{\mathrm{o}} are positive for all investigated concentrations of aqueous FM and AM solutions. However, values for D[`(C)]_p2,tr^o\Delta\overline{C}_{p\mathrm{2,tr}}^{\mathrm{o}} associated with aqueous DMA solutions are found to be negative. The reported transfer properties increase with increasing co-solute (amide) concentration. This observation is discussed in terms of solute + co-solute interactions. The transfer properties have also been used to estimate interaction coefficients.     

Magnesium–lithium alloys with TiB and Sr additions

The ultralight hypoeutectic α-phase Mg–4.5Li–1.5Al alloy and hypereutectic β-phase Mg–12Li–1.5Al alloy in as-cast state were fabricated and subjected to modification by 0.2 mass% TiB and 0.2 mass% Sr grain modifiers. The crystallisation sequence of Mg–Li–Al alloys has been investigated in detail by using thermal-derivative analysis and microstructural observations. The presented work includes the effects of grain refiners on grain size and microstructure and thermal events registered during crystallisation of ultralight Mg–Li–Al alloys by recording and analysis of the temperature vs time, i.e. as T_N, T_α, T_β, T_η(LiAl) and T_SOL. Microstructure and phase observation has been done by light microscope, X-ray diffraction and energy dispersive X-ray spectroscopy. The changes of characteristic temperature points for phase transformation are studied in detail. Due to the addition of 0.2 mass% TiB and 0.2 mass% Sr, the grain structure of the alloy was refined, and mechanical properties were improved. When a TiB and Sr added simultaneously, the average grain size of the analysed alloys strongly decreases. When the TiB or Sr content was severally added, a low effect of improvements of mechanical properties was observed. With the TiB and Sr content, the liquidus and solidus decrease gradually.

     

Cs, Am and Pu isotopes as tracers of sedimentation processes in the Curonian Lagoon–Baltic Sea system

¹³⁷Cs, ²⁴¹Am and Pu isotopes were analyzed in seawater, bottom sediments (BS) and suspended particulate matter samples collected in the Baltic Sea during 1997–2011. The particle size distribution and sequential extraction studies were carried out with the aim to better understand the association of radionuclides with particles and their bonding patterns in the BS. δ¹³C_org was applied for identification of sources of organic matter in the studied area. It has been found that massic activities of ¹³⁷Cs in BS varied from 2.1 to 588 Bq/kg. High correlation of ¹³⁷Cs massic activities with total organic carbon (TOC) in BS (r = 0.75) and with clay minerals (r = 0.95) was found. ^239,240Pu massic activities in BS varied from 0.03 to 7.5 Bq/kg. High correlation with TOC was found for ^239,240Pu (R = 0.98) as well as for ²⁴¹Am (r = 0.96). δ¹³C_org in the studied samples ranged from ?22.3 to ?31.8 ‰.