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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. L. Bonardi, F. Groppi, H. S. Mainardi, V. M. Kokhanyuk, E. V. Lapshina, M. V. Mebel, and B. L. Zhuikov

Summary  

High specific activity 64Cu is a radionuclide of increasing interest for PET imaging, as well as systemic and targeted radioimmunotherapy of tumours. The cross sections for production of 64Cu from Zn target of natural isotopic composition were measured in the proton energy range from 141 down to 31 MeV. The stacked-foil technique was used at 160 MeV intersection point of INR proton-LINAC in Troitsk, Russia. Several Ga, Zn, Cu, Ni, Co, V and Mn RNs were detected in Zn targets at the EOB. The activity of no-carrier-added 64Cu was measured through its only gamma-emission of 1346 keV (0.47% intensity). To this purpose, it was necessary to carry out a selective radiochemical separation of Ga RNs from the bulk of irradiated Zn target and other RNs. Theoretical calculations of cross sections were carried out with the CEF model and HMS-ALICE hybrid model codes and are compared with the experimental values.

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Abstract

It is well established that gallium insertion into the hydroxiapatite matrix as practiced in orthopedics protects bone from resorbtion and improves the biomechanical properties of the skeletal system. The research presented in this article is an investigation into the thermal decomposition of gallium nitrate, which is part of a complex process leading to the preparation of a hybrid matrix. It was demonstrated that after melting of the hexahydrate in its own water there occurs a simultaneous condensation of 4 mol of initial monomer Ga(NO3)3·6H2O into a tetramer Ga4O4(NO3)4. The resulting inorganic cycle gradually loses N2O5 and, through the formation of unstable oxynitrates, is transformed into gallium oxide. The use of molecular mechanics for comparing the potential energies of consecutive products of thermal decomposition permitted an evaluation of their stability and an appropriate interpretation of the experimental data.

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Abstract  

We measured from 5 to 300 K the thermal conductance of different superconducting Bi-2212 thin rods and one superconducting module integrating a hybrid current lead based on such rods. The conductance values of the rods are lower than the measurable limits of the set-up and a detailed evaluation of the heat losses is required. The analysis of the heat exchanges permits to introduce a correction function to the measured values and allows to study low thermal conductivity materials. The dependence of the thermal conductivity of Bi-2212 rods on the sample microstructure is analyzed after this correction. We calculate analytically the time required to reach the steady-state for long bars for which extended relaxation times are expected. From the measured conductance data we estimate the heat load introduced by the current lead into a cryogenic bath in static conditions.

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Abstract  

Samples of an organic–inorganic hybrid were prepared by solvolysis and polycondensation in formic acid of tetraethoxysilane and diethylbenzyl phosphonate, simultaneous with the oxidative polymerization of aniline. The thermal behavior of the samples in dynamic air atmosphere and non-isothermal conditions was determined by a coupled thermogravimetric/evolved gas analysis. Two significant thermal events were established: the elimination from the polymeric matrix of low mass molecules, respectively the thermooxidative degradation of the organic part of the matrix. The kinetic analysis was performed with the Flynn-Wall-Ozawa, Friedman and modified Non-Parametric-Kinetic methods. Only the last one allowed an objective analysis of the first process as a process of two simultaneous thermally induced phenomena with the kinetic functions of the type αm(1 − α)n.

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Abstract  

Bentonite was investigated to remove Ni(II) from aqueous solutions because of its strong sorption ability. Herein, bentonite was modified with sodium carboxymethylcellulose (CMC) and used as an adsorbent to remove Ni(II) from aqueous solutions. The results indicated that CMC-bentonite had higher sorption capacity than bare bentonite in the sorption of Ni(II) from aqueous solutions. Sorption of Ni(II) on CMC-bentonite was mainly dominated by ion exchange or outer-sphere surface complexation at low pH values, but by inner-sphere surface complexation or surface precipitation at high pH values. The thermodynamic data calculated from temperature dependent sorption isotherms indicated that the sorption of Ni(II) to CMC-bentonite hybrids was an spontaneous process and enhanced with increasing temperature.

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Abstract  

In divalent tin halides, when the halogen is small and highly electronegative (F, Cl), the tin valence orbitals are hybridized, the tin(II) non-bonded electron pair is located on one of the hybrid orbitals, and the resulting large electric field gradient gives a large quadrupole splitting. The reaction of barium chloride and tin difluoride in aqueous solutions, for large BaCl2.2H2O/SnF2 ratios (>10) results in the precipitation of a white powdered material, which is identified by X-ray diffraction to be BaCIF. However, Tin-119 Mossbauer spectroscopy shows the material contains a fairly large amount of divalent tin in the Sn2+ ionic form, with unhybridized orbitals, like in SnCl2. Using X-ray diffraction, we have established that Sn2+ ions substitute 15% of the Ba2+ ions at random, and chemical analysis shows the material has the formula Ba5.66SnCl7.30F6.04 and thus is enriched in chlorine.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Ştefănescu, M. Stoia, O. Ştefănescu, A. Popa, M. Simon, and C. Ionescu

Abstract  

Hybrid organic-inorganic materials, silica – polyols (ethylene-glycol – EG; 1,2 propane diol – 1,2PG; 1,3 propane diol – 1,3PG and glycerol – GL), were prepared by a sol-gel process starting from tetraethylorthosilicate (TEOS) and polyols, in acid catalysis. The resulting materials were studied by thermal analysis (in air and nitrogen), FTIR and solid state 29Si-NMR spectroscopy. These techniques evidenced the presence of polyols in the silica matrix both hydrogen bounded and chemically bounded in the silica network. The thermal analysis proves to be the most appropriate technique to evidence the organic chains linked in the matrix network and to follow the thermal evolution of the gels to the SiO2 matrix.

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To simulate front displacement through porous media (TLC plates) the effect of the axisymmetric alternating electric fields on liquids confined in capillary tubes was studied. This electric field causes liquid displacement through capillary tubes with great velocity, the main action being on the liquid column meniscus. Capillary tubes were used to enable understanding of the flow phenomena which occur in porous media. It was observed that the displacement velocity of the liquids confined in capillary tubes depended on the magnitude of the alternating electric field, the electric properties (conductivity, permittivity) of the liquids, the frequency of the current, and the tube material.In normal TLC practice, migration of the mobile phase through the layer is controlled by capillary forces. The velocity and migration distance of the mobile-phase front in prous media can be increased by application of an external electric field, an effect called by us ‘dielectroosmotic flow’ (DEOF), because of its similarity with electrokinetic phenomena. DEOF is observed on different TLC plates and paper strips developed with non-polar and polar solvents. As a result the separation of some compounds was improved. This method is a hybrid of electric forced flow and classical TLC; we have named it ‘planar dielectrochromatography’ (PDEC).A horizontal chromatographic chamber has been constructed and has been used to investigate the principles of planar dielectrochromatography, specifically the increase in front velocity and the dielectrophoretic force generated at granule level on different ready-to-use plates.

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Abstract  

61Cu is positron emitter and can be used as the PET and molecular imaging. In this study cyclotron production of 61Cu via 61Ni(p,n)61Cu, natNi(p,x)61Cu, natNi(d,x)61Cu, natNi(α,x)61Cu, natZn(p,x)61Cu and 59Co(α,2n)61Cu reactions was investigated. The ALICE/ASH (hybrid and GDH models) and TALYS-1.2 codes were used to calculate excitation functions for proton, alpha and deuteron induced on natNi, proton on 61Ni and natZn and also alpha-particle on 59Co targets that lead to the production of 61Cu radioisotopes using intermediate energy accelerators. In addition, we compared the data obtained from in this study with the reported measurement by experimental data. Moreover, optimal thickness of the targets and physical yield were obtained by stopping and range of ions in matter code for each reaction. Eventually 61Ni(p,n)61Cu and 59Co(α,2n)61Cu reaction to produce 61Cu in no-carrier added state with high production yield was suggested. Finally the natNi(p,x)61Cu reaction was employed to test the target preparation using electroplating technique.

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Abstract  

We report on the design, construction, and testing of a gamma-ray imaging system with spectroscopic capabilities. The imaging system consists of an orthogonal strip detector made from either HgI2 or CdZnTe crystals. The detectors utilize an 8×8 orthogonal strip configuration with 64 effective pixels. Both HgI2 or CdZnTe detectors are 1 cm2 devices with a strip pitch of approximately 1.2 mm (producing pixels of 1.2 mm × 1.2 mm). The readout electronics consist of parallel channels of preamplifier, shaping amplifier, discriminators, and peak sensing ADC. The preamplifiers are configured in hybrid technology, and the rest of the electronics are implemented in NIM and CAMAC with control via a Power Macintosh computer. The software used to readout the instrument is capable of performing intensity measurements as well as spectroscopy on all 64 pixels of the device. We report on the performance of the system imaging gamma-rays in the 20–500 keV energy range and using a pin-hole collimator to form the image.

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