New ferromagnetics based on manganese-alloyed chalcopyrites A<Superscript>II</Superscript>B<Superscript>IV</Superscript>C<Stack><Subscript>2</Subscript><Superscript>V</Superscript></Stack>

This review describes the principles of semiconductor spintronics, represents the physicochemical properties of materials based on manganese-alloyed A^IIB^IVC₂^V compounds, considers the results from theoretical simulation of magnetic properties of A^IIB^IVC₂^V alloyed with 3d metals, summarizes the basic approaches to explanation of ferromagnetism with Curie points above room temperature arising in A^IIB^IVC₂^V:Mn, and indicates promising ways to synthesize and study magnetic semiconductors based on chalcopyrites A^IIB^IVC₂^V in order to produce a suitable material for spintronic devices.     

Desorption of 90Sr and 137Cs from Flood Plain Deposits of the Sozh River and Rocks of the Adjacent Catchment Areas

Desorption of ⁹⁰Sr and ¹³⁷Cs from flood plain warps, meadow sod, humus-containing sandy loam, peat, clays, limonite, meadow marl, and friable rocks of the adjacent catchment areas (moraine clay, loam, sandy loam) was studied. ¹³⁷Cs is sorbed the most strongly on clays by the mechanism of isomorphic ion-exchange incorporation into the crystal lattice of montmorillonite-type minerals. ¹³⁷Cs is also tightly fixed on buried and peaty soils due to association with the poorly mobile species of humic acids and humin. The strong fixation of ⁹⁰Sr on amorphous iron hydroxides is caused by its association with poorly soluble ferrite-type minerals. Sorption of ⁹⁰Sr on peaty soils can be attributed to their association with aluminum and iron-containing organomineral complexes. ¹³⁷Cs sorbed on flood plain warps, sandy loams, and loams exhibits increased mobility and is leached with all the tested desorbing solutions. These deposits apparently contribute maximally to the redistribution of radiocesium over flood plain and the adjacent catchment areas. The desorption efficiency of cations of the desorbing solutions decreases in the order Cs⁺ > K⁺ > Fe^{3 +} > NH₄ ⁺ > Ca^{2 +} > H⁺ for radiocesium and Fe^{3 +} > Sr^{2 +} > K⁺ > H⁺ > Ca^{2 +} > NH₄ ⁺ for radiostrontium.     

Behavior of Trace Amounts of Cd and Zn in Sorption and Coprecipitation in Tetrahydrofuran Solutions

Sorption of trace amounts of ¹⁰⁹Cd and ⁶⁵Zn on zeolites NaX and NaA in the presence of divalent lanthanides Ln²⁺ (Ln = Tm, Dy, Nd) from tetrahydrofuran (THF) solutions is studied. In contrast to ¹³⁷Cs⁺ and similar to ⁸⁵Sr²⁺, trace amounts of ¹⁰⁹Cd and ⁶⁵Zn are not practically sorbed on zeolites (about 99% of these radionuclides remains in the solution). The distribution coefficients K _d of ¹⁰⁹Cd and ⁶⁵Zn are ∼0.3 and ∼0.4 ml g⁻¹, respectively. In THF solutions, Tm²⁺ is oxidized to Tm³⁺, and TmI₃ ⋅ 3THF is precipitated. Study of cocrystallization of trace amounts of ¹⁰⁹Cd and ⁶⁵Zn and also of ⁸⁵Sr with this precipitate from THF solutions containing Tm²⁺ revealed that, in contrast to ⁸⁵Sr²⁺, ¹⁰⁹Cd and ⁶⁵Zn traces cocrystallize with the solid solvate phase. The cocrystallization coefficients D of ¹⁰⁹Cd and ⁶⁵Zn increase with increasing Tm³⁺/Tm²⁺ ratio in the solution. The mechanism suggested is that, in the presence of Tm²⁺, ¹⁰⁹Cd²⁺ and ⁶⁵Zn²⁺ are reduced to single-charged cations M⁺, which then rapidly react with the double-charged cations M²⁺ with the formation of dimers M ₂ ³⁺ (M = Cd, Zn).__________Translated from Radiokhimiya, Vol. 47, No. 3, 2005, pp. 261–264.Original Russian Text Copyright © 2005 by Veleshko, Kulyukhin.     

Influence of Ce on the luminescence properties of Er/Yb:YVO4 crystals

YVO₄ single crystals doped with Ce³⁺, Er³⁺ and Yb³⁺ ions were grown by the Czochralsski technology. The luminescence properties of Er³⁺/Yb³⁺:YVO₄ single crystals with different concentration of Ce³⁺ were studied, and the energy transfer mechanism between Er³⁺, Yb³⁺ and Ce³⁺ was discussed based on their energy level properties. The branching ratios of the ⁴I_11/2 → ⁴I_13/2 transition in different samples were calculated. The results indicate that codopants of Ce³⁺ greatly enhance the population rate of the ⁴I_13/2 level due to the fast resonant energy transfer between Er³⁺ and Ce³⁺, i.e., ⁴I_11/2(Er³⁺) + ²F_7/2(Ce³⁺) → ⁴I_13/2(Er³⁺) + ²F_5/2(Ce³⁺).     

Behavior of radioaerosols formed by evaporation of 137Cs131I and 137CsOH from the metal surface in an electrostatic field

The behavior of radioaerosols formed by condensation of supersaturated ¹³⁷Cs¹³¹I and/or ¹³⁷CsOH vapor in an electrostatic field was studied. Supersaturated ¹³⁷Cs¹³¹I and/or ¹³⁷CsOH vapor was generated by evaporation of salt crystals from a metal surface heated to high temperatures owing to ohmic resistance. By applying additional potential to the aerosol generator, it is possible to control the behavior of ¹³⁷Cs¹³¹I, ¹³⁷CsOH, or ¹³⁷Cs¹³¹I + ¹³⁷CsOH aerosols in an electrostatic field.     

船用结构钢合金成分优化及耐微生物腐蚀性能研究

为了优化船用结构钢合金元素,提高其耐微生物腐蚀性能,研究了船舶用结构钢冶炼中常见的10种重金属元素对海洋微生物生长的抑制能力,探讨了金属离子毒性与细菌胞外分泌物(EPS)选择吸附的关系,并采用电化学、倒置荧光显微镜和原子力显微镜分析了经过合金元素优化后的试样的耐微生物腐蚀性能。实验结果表明,金属离子抑制毒性与 EPS 的选择吸附有密切关系,EPS 对这些金属离子的吸附能力越强,该金属离子对细菌的毒性就越大;对于革兰氏阴性菌而言,各重金属离子的毒性大小为 Cu2+> Zn2+>Ni2+>Pb2+>Cr3+>V5+>Co2+>Mo6+>Mn2+> Al3+,对于革兰氏阳性菌而言,各重金属离子的毒性大小为 Ni2+> Zn2+> Cu2+> Co2+> Cr3+>Pb2+>V5+> Mn2+> Mo6+> Al3+;优化 Ni、Cu、Cr 三种合金元素在试样中的含量,在一定程度上均可以加强试样在无菌介质和有菌介质中的耐腐蚀性能。同时提高合金元素 Ni、Cu 和 Cr 在钢材中的含量对于提高材料的耐微生物附着腐蚀性能最为显著。     

Synthesis and X-ray Diffraction Study of Mixed-Metal Orthophosphates with NaZr2(PO4)3 and CePO4 Structures

Mixed-metal orthophosphates with Ca^{2 +}, Cd^{2 +}, Gd^{3 +}, Ti^{4 +}, Hf^{4 +}, Ce^{4 +}, U^{4 +}, and Pu^{4 +} were synthesized and studied by X-ray diffraction. Crystalline compounds containing cerium or plutonium, or both these elements were prepared. Cerium was taken as an imitator for plutonium. The phosphates containing Ti^{4 +} and Hf^{4 +} formed two-phase systems. One of the phases was assigned to the Zr₂(PO₄)₃ structural type (NZP), and the other phase, to the CePO₄ type (monazite). In the other cases, single-phase products were formed. The effect of the cationic composition on the crystal structure of the complex orthophosphates, including the unit cell parameters of the crystalline phases, was studied.     

The State of Disequilibrium between U and Th Series Isotopes in Marine Sediments from the Sudanese Red Sea Coast

The geochemical behavior of U, Th series nuclides in surface marine sediments collected fromthe Red Sea coastal environment of Sudan was examined using daughter/parent and nonisotopic activity ratios. Pronounced anomalous behavior of several series of nuclides has been observed, particularly at shallower depths. On the average, the ²³⁴U/²³⁸U ratio is fairly constant and close to 1.13, suggesting scavenging of ²³⁴U from the overlying water column. In shallow-water sediments collected from the biologically productive area of the fringing reef and from the tidal-flat of Sanganeb atoll, compared to harbor and deep-sea sediments, ²³⁸U was found in large excess relative to ²³²Th. The ²²⁸Th/²³²Th disequilibrium indicates rapid sedimentation at shallower sites, which agrees well with data reported in the literature for similar environments. Depletion was observed of precursor thorium isotopes (²³⁰Th, ²³²Th) with respect to their mobile daughter isotopes of radium (²²⁶Ra, ²²⁸Ra). On the other hand, there is surface enrichment of ²²⁸Th and ²¹⁰Po with respect to their progenitors ²²⁸Ra and ²²⁶Ra, as demonstrated by the ²²⁸Th : ²²⁸Ra and ²¹⁰Po : ²²⁶Ra activity ratio, which is greater than unity in all the sediments analyzed. The ²¹⁰Po/²²⁶Ra ratio is fairly constant (average 3.2).     

Radionuclides in ground waters from observation holes in the Shelter local area

The volume activity of ³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁴U, ²³⁵U, ²³⁸U, ²³⁸Pu, ^239+240Pu, and ²⁴¹Am in ground waters from observation holes 1-G-6-G in the north section of the Shelter local area of the Chernobyl Nuclear Power Plant (CNPP) was measured. The distribution of radionuclides in the suspension fractions of the ground waters was evaluated. The main contribution to the pollution of ground waters with uranium is due to natural uranium isotopes: ^234,235,238U. The activity ratios of ²³⁸Pu, ^239+240Pu, and ²⁴¹Am in ground waters are similar to those in the spent fuel of 4th CNPP block.     

Association of 90xSr, 137Cs, 239,240Pu, 241Am,and 244Cm with Soil Absorbing Complex in Soils Typical of the Vicinity of the Chernobyl NPP

Association of the main long-lived radionuclides ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu, ²⁴¹Am, and ²⁴⁴Cm with various components of the soil absorbing complexes from soil samples collected along the western, northwestern, and northern tracks of radioactive fallout in the vicinity of the Chernobyl NPP was studied by the sequential leaching. In the samples of the sandy soil collected in the floodplain of the Pripyat river along the northwestern radioactive track, more than 85% of ⁹⁰Sr, 55% of ^239,240Pu, and 75% of ²⁴¹Am and ²⁴⁴Cm are associated with various components of the soil absorbing complex and are potentially mobile species. In the soil samples collected along the narrow western track, 80-85% of ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu, ²⁴¹Am, and ²⁴⁴Cm are incorporated in hot particles. The degree of ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu, ²⁴¹Am, and ²⁴⁴Cm association with different components of the soil absorbing complex is a function of the radionuclide type and physicochemical features of soil.     

Spatial distribution of radionuclides produced in copper by photonuclear spallation reactions

The spatial distribution of radionuclides produced in a 15 cm thick copper target, which is commonly used as accelerator material, was measured by bombarding the bremsstrahlung radiation generated by 900 MeV electrons. The production of radionuclides of ⁶⁴Cu, ⁶¹Cu, ⁶⁰Cu, ⁵⁸Co, ⁵⁷Co, ⁵⁵Co, ⁵⁶Mn, ⁵²Mn, ⁴⁸Sc, ⁴⁷Sc,and ^44mSc was clearly identified up to about 10 cm in depth. The spatial distribution of bremsstrahlung radiation in copper was also calculated by the electromagnetic cascade Monte Carlo code, EGS-4. By comparing the experimental data and the calculated results, the effective cross sections and the effective energy ranges were derived for ⁶⁵Cu(γ,n)⁶⁴Cu, ⁶³Cu(γ,2n)⁶¹Cu, ⁶³Cu(γ,3n)⁶⁰Cu and other photonuclear spallation reactions.     

Absorption Bands of Carbon Dioxide From 5.3 to 4.6 Microns

Measurements have been made of the frequencies of the infrared absorption lines of CO₂ in the region from 1850 cm⁻¹ to 2150 cm⁻¹. Observations were made at various pressures and pathlengths up to a maximum of 72 meter-atmospheres. Vibration-rotation constants were obtained characterizing the transitions 11^1c0–000, 11^1d0–000, 03^1c0–000, 03^1d0–000, 200–01^1c0, I2^2c0–01^1c0, 12^2d0–01^1d0 for C¹²O₂. The 11^1c0–000 band due to the C¹³O₂ molecule was also measured.     

Enhanced green emission from Tb-Bi co-doped GdAlO3 nanophosphors

Bi³⁺ and Tb³⁺ ions co-doped GdAlO₃ (GAP) nanophosphors have been synthesized by means of solvothermal reaction method. The XRD pattern of GAP phosphor confirms their orthorhombic phase. The luminescence properties of these phosphors have been explored by analyzing their excitation and emission spectra along with their decay curves. The excitation spectra of GAP:Tb³⁺, Bi³⁺ phosphors consist of a broad band in the shorter wavelength region due to the 4f⁸ → 4f⁷5d¹ transition of Tb³⁺ ions overlapped with the 6s² → 6s¹6p¹ (¹S₀ → ³P₁) transition of Bi³⁺ ions and some sharp peaks in the longer wavelength region due to f → f transitions of Tb³⁺ ions. The present phosphors exhibit green color due to strong ⁵D₄ → ⁷F₅ transition of Tb³⁺ ions. The emission intensity was enhanced by co-doping with Bi³⁺ ions under 292 nm excitation, which indicate that the efficient energy transfer occurred from Bi³⁺ to Tb³⁺ ions.     

Cocrystallization of Radioiodine Compounds from the Gas Phase

The study of the behavior of ¹³⁷Cs¹³¹I in the presence of MCl (M = NH₄ ⁺, K⁺, Ag⁺, and Cu⁺) in the water vapor-gas phase showed that CsI aerosols are localized in the MCl matrix owing to both agglomeration cocrystallization [¹³⁷Cs¹³¹I-MCl systems (M = K⁺, Ag⁺, NH₄ ⁺)] and agglomeration capture [¹³⁷Cs¹³¹I-CuCl system]. The main advantage of the first process is formation of crystalline globules encapsulating radioiodine in their bulk, which prevents transformation of radioiodine into elemental iodine and methyl iodide.     

Orthorhombic electron spin resonance spectra of gadolinium ions in CdF2

The ESR spectra of Gd³⁺1bNa⁺ were measured in GdF₂ crystals, in which Na⁺ ions, compensating for the Gd³⁺ charge, occupy the nearest-neighbor Cd²⁺ sites. The b^m_n Hamiltonian constants were evaluated. The orthorhombic symmetry of neighborhood of the impurities was compared for the Na⁺-compensated Gd³⁺1bNa, and the O^2?-compensated Gd³⁺1bGd³⁺ impurities.     

Production of 2-[18F]Fluoro-2-deoxy-D-glucose at the Laboratory of Radiochemistry, University of Helsinki

Production 2-[^{1 8}F]fluoro-2-deoxy-D-glucose ([^{1 8}F]FDG) was started at the Laboratory of Radiochemistry in 1998 when a cyclotron, specially designed for the production of short-lived positron emitters, was bought to the laboratory. The radiosynthesis of [^{1 8}F]FDG is based on aminopolyether-mediated nucleophilic fluorination. [^{1 8}F]Fluoride is produced by the ^{1 8}O(p,n)^{1 8}F nuclear reaction. [^{1 8}F]FDG is synthesised with an automated device. The radiochemical yield of the synthesis is 50% (by the end of bombardment). Sterile and isotonic [^{1 8}F]FDG solution is produced within 55 min. [^{1 8}F]FDG is delivered for patient use by the medical company MAP Medical Technologies.     

Fabrication of electrically conductive membrane electrode of gelatin-tin (IV) phosphate nanocomposite for the detection of cobalt (II) ions

Gelatin-tin (IV) phosphate nanocomposite (GT/TPNC) ion exchanger was synthesized by mixing gelatin gel into the precipitates of tin (IV) phosphate using sol–gel method. GT/TPNC was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ion exchange capacity of GT/TPNC was reported to be1.44?meq/g. The material was found monofunctional as indicated from pH titration curves. The distribution coefficient of different metal ions such as Zn²⁺ (42.10), Cd²⁺ (37.93), Mg²⁺ (33.33), Cu²⁺ (33.21), Al³⁺ (14.28), Pb²⁺ (6.06), Ni²⁺ (12.50) and Co²⁺ (50.0) was studied using GT/TPNC ion exchanger. The distribution studies confirmed the selectivity of GT/TPNC for Co (II). The photocatalytical degradation of MB was found to be 78% within 5 h of solar illumination using GT/TPNC. Some binary separations such as Co²⁺–Pb²⁺, Cd²⁺–Ni²⁺, Co²⁺–Mg²⁺, Mg²⁺–Zn²⁺, Pb²⁺–Zn²⁺, Cu²⁺–Al³⁺, Al³⁺–Cd²⁺, Ni²⁺–Cu²⁺ were attempted using GT/TPNC ion exchanger. GT/TPNC was explored for the fabrication of ion-sensitive membrane electrode for the determination of Co (II) in the water system. The membrane electrode was found mechanically more stable with quick response time (30?s) and a wide pH working range (4.0–7.0).     

Soil Contamination with Fuel Component of Chernobyl Radioactive Fallout

Radionuclide activity ratios in the fuel component of the Chernobyl fallout are reestimated on the basis of new experimental data, and maps of the density of contamination of the Chernobyl 30-km zone with ¹⁵⁴Eu, ²³⁸Pu, ^239+240Pu, and ²⁴¹Am as of January 1, 2000 are compiled. The total radionuclide inventories in the top 30-cm horizon of the soil of the 30-km zone (minus the NPP service area, cooling pond, and radioactive waste disposal sites) on January 1, 2000 were estimated to be (Bq): ⁹⁰Sr 7.7×10^{1 4}, ¹³⁷Cs 2.8×10^{1 5}, ¹⁵⁴Eu 1.4 × 10^{1 3}, ²³⁸Pu 7.2 × 10^{1 2}, ^239+240Pu 1.5 × 10^{1 3}, and ²⁴¹Am 1.8 × 10^{1 3}, which makes up to 0.4-0.5% of the total amount of these radionuclides produced in the 4th block of CNPP. This value is lower by a factor of 3 than that generally accepted so far. The radionuclide inventories in other objects of the 30-km zone and beyond it are also estimated. The total amounts of radionuclides fallen out with fuel particles beyond the NPP service area are reestimated. The resulting value (1.5±0.5% of the total produced in the reactor by the accident time) is lower by half as compared to the previous estimates. Two thirds of these amounts are found on the Ukrainian territory.     

Highly selective ion-imprinted particles for solid-phase extraction of Pb ions

The Pb²⁺-imprinted (PHEMAC-Pb²⁺) particles were prepared by bulk polymerization as a solid-phase extraction (SPE) adsorbent. N-methacryloyl-(l)-cysteine (MAC) was used as functional monomer to have a well-shaped molecular geometry between MAC monomer and Pb²⁺ ions that provide molecular recognition based on well fitted cavities for Pb²⁺ ions after removal of template ions. The PHEMAC-Pb²⁺ particles were characterized and the applicability of these particles was investigated for the solid-phase extraction of Pb²⁺ ions from aqueous solutions and environmental samples. The PHEMAC-Pb²⁺ particles with a size range of 50–200 µm have a rough surface and macropores in bulk structure. The adsorption capacity of the PHEMAC-Pb²⁺ particles is relatively low (2.01 mg/g). However, the high selectivity towards competitive ions (Cd²⁺, Ni²⁺ and Cu²⁺) promises the PHEMAC-Pb²⁺ particles an alternative SPE adsorbent in literature. The relative selectivity coefficients of PHEMAC-Pb²⁺ particles for Pb²⁺/Ni²⁺, Pb²⁺/Cd²⁺ and Pb²⁺/Cu²⁺ were almost 71, 117 and 192 times greater than that of non-imprinted (PHEMAC) particles, respectively. Moreover, the reusability of the PHEMAC-Pb²⁺ particles was tested for several times and no significant loss in adsorption capacity was observed. The accuracy of the proposed procedure was also verified by the determination of Pb²⁺ ions in the certified reference material, LGC 6137 Estuarine sediment.     

Production of Neptunium and Plutonium Tracers in Nuclear Reactions of 236U with 21-to-60-MeV 3He Ions1

Production of ²³⁶Pu, ²³⁷Pu, and ²³⁵Np by the reactions ²³⁶U(³He,t^-)²³⁶Pu, ²³⁶U(³He,2n)²³⁷Pu, and ²³⁶U(³He,p3n)²³⁵Np with 43- and 60-MeV ³He ion beams on the K-130 cyclotron of the University of Jyvüaskylüa was studied. The cross sections for the reactions were determined. The curves of yields with thick targets were derived from the cross sections. The results are discussed and compared with previous data on the other reactions yielding the same final products.