Development of an automated unit for extraction-chromatographic separation of the 99Mo/99m Tc generator couple

The design and automatic control scheme were developed for an extraction-chromatographic unit for producing ^99m Tc preparations. The unit is intended for operation under the conditions of medical radiological laboratories. Technical trials showed that the mean time of preparation of sodium [^99m Tc]pertechnetate radiopharmaceutical did not exceed 25 min.     

Synthesis and properties of 99Tc(I) and 99m Tc(I) hexacarbonyl in aqueous solutions

A procedure was developed for preparing Tc(CO)₆ClO₄ by carbonylation of a solution of technetium(I) tricarbonyltriaqua complex in 2 M HClO₄ in a pressure vessel at 100–170°C and CO pressure of 150 atm. The hexacarbonyltechnetium cation in solution was characterized by IR and ⁹⁹Tc NMR spectroscopy, and also by high-performance liquid chromatography (HPLC). The effect of particular acid and of synthesis conditions on the yield of the hexacarbonyltechnetium cation was examined, and the stability of this cation in aqueous solutions was evaluated. Conditions were found for preparing an aqueous solution containing ^99m Tc(CO) ₆ ⁺ .     

Synthesis and photocatalytic properties of nanomaterials based on titanium(IV) and cerium(IV) oxides

We have studied the phase transitions, morphology, and photocatalytic activity of titanium(IV) oxide–cerium(IV) oxide materials at Ce doping levels from 1 to 20 wt % and heat-treatment temperatures from 80 to 1150°C. The highest photocatalytic activity under illumination in the spectral range λ ≥ 670 nm is offered by mesoporous X-ray amorphous and multiphase (X-ray amorphous phase + anatase + rutile + CeO₂) nanomaterials, whereas the two-phase materials (rutile + CeO₂) have the lowest photocatalytic activity.     

A procedure for sorbent pretreatment for the production of high-activity 99Mo/99m Tc generators based on enriched 98Mo

The effect of the acid treatment on the adsorption capacity of aluminum oxides for Mo was examined. The areas of the initial (??_o) and limiting (??_lim) saturation of neutral and acidic aluminum oxides with hydrochloric acid were determined. The Mo adsorption maximum is attained at the limiting saturation, with the subsequent exponential decrease on approaching the point in which the interaction of the oxide with the acid starts to decelerate, after which the adsorption drastically decreases. In the area close to ??_o, the Mo breakthrough to the eluate is observed at any adsorbed amount of Mo. The results obtained allow prediction of the acid amount required for the adsorption of the preset amount of Mo.     

Preparation of 99Mo and 99m Tc by 100Mo(γ,n) photonuclear reaction on an electron accelerator, MT-25 microtron

Molybdenum-99 was prepared by ¹⁰⁰Mo(γ,n) photonuclear reaction on an electron accelerator, MT-25 microtron (FLNR). Natural Mo foil (9.6% ¹⁰⁰Mo) and ¹⁰⁰MoO₃ (100% ¹⁰⁰Mo) were used as the targets. The radiation yield of ⁹⁹Mo was 3.2 kBq/(μA h mg ¹⁰⁰Mo). Technetium-99m was isolated from the target material and concomitant radioactive impurities by an ion-exchange procedure. The possibility of preparing ^99m Tc generator from molybdenum carbonyl was studied. The content of radioactive impurities in the final ^99m Tc preparations was no higher than 10^?5 Bq Bq^?1.     

聚合物/Fe3O4混合体系高能球磨过程的穆斯堡尔谱研究

运用高能球磨法研磨聚合物／Fe3O4混合体系，对样品的穆斯堡尔谱与XRD的测定表明有纳米级α-Fe2O3颗粒生成；通过改变聚合物种类、比例以及球磨气氛从不同角度考察聚合物对Fe2O4球磨的影响。     

Sorption of Mo(VI) on zirconium molybdosilicate gel and potential application as a <Superscript>99</Superscript>Mo/<Superscript>99<Emphasis Type="Italic">m</Emphasis> </Superscript>Tc generator

Sorption of Mo(VI) from aqueous nitrate solutions onto zirconium molybdosilicate (ZrMoSi) gel was studied using ⁹⁹Mo radiotracer. The acid–base titration curve showed that the prepared ZrMoSi gel was an amphoteric material with the point of zero charge (PZC) at pH 2.5. The highest distribution coefficient (600 mL g^–1) of ⁹⁹Mo(VI) on ZrMoSi from nitrate media was achieved at pH 2.1. The sorption kinetics of ⁹⁹Mo(VI) onto ZrMoSi obeyed the pseudo-second-order model. The breakthrough sorption capacity of ZrMoSi gel was found to be 4.25 × 10^–2 [mmol Mo(VI)] g^–1. The prepared ⁹⁹Mo/^99mTc chromatographic column generator showed a good performance: The ^99mTc elution yield was 87.7%, pH of the eluate ranged from 5.6 to 7.2, and the radionuclidic purity of the eluted ^99mTc was >99.99% with a radiochemical purity of 98.31% (as ^99mTcO₄^–).     

Ligand-exchange chromatography at zirconium(IV) immobilized on IDA-type chelating polymer gel

Ligand-exchange chromatography of organo-acidic compounds at Zr(IV) immobilized on IDA-type chelating polymer gel using an aqueous mobile phase was studied, to obtain some insight into their retention on zirconia. Zirconium(IV) has no contribution to the retention of phenols, while appreciably enhancing that of benzoic acids and strongly or occasionally irreversibly adsorbing the potentially chelating substances. The presence of two stationary-phase species adsorbing benzoates was confirmed, and the retention over a wide pH range of 3.5-9.5 was quantitatively formulated. The correlation of the retention factor with the Bronsted acidity of samples and its dependence on pH were theoretically explained, and the performance of this chromatographic system was compared with that of zirconia.     

Salicylate-selective membrane electrode based on tin(IV) tetraphenylporphyrin

The response properties of a new solvent/polymeric membrane electrode with unique selectivity toward anionic salicylate are reported. The electrode is prepared by incorporating 5, 10, 15, 20-tetraphenyl(porphyrinato)tin(IV) dichloride (Sn[TPP]Cl2) into a plasticized poly(vinyl chloride) membrane. The resulting sensor exhibits an anti-Hofmeister selectivity pattern, with high specificity for salicylate over lipophilic inorganic anions (perchlorate, periodate, thiocyanate, iodide, etc.) and biological organic anions (citrate, lactate, acetate). Moderate selectivity over structural analogues of salicylate (3- and 4-hydroxybenzoate, benzoate) is also observed. Radiotracer uptake experiments using [14C]salicylate clearly show that the metal center of the metalloporphyrin is critical for selective salicylate transport in the membrane phase. Minimal response to chloride ions makes the new electrode potentially useful for estimating salicylate levels in biological samples.     

A hybrid microwave generator based on a vircator-TWT (Virtode) system

Various schemes of microwave generators (TWT, vircator, and a vircator-TWT hybrid virtode) were studied in operation under the same power supply conditions. It is demonstrated that the virtode offers the most efficient solution.     

Salicylate-selective electrodes based on AI(III) and Sn(IV) salophens

New salicylate-selective electrodes based on aluminum-(III) and tin(IV) salophens are described. The electrodes were prepared by incorporating the ionophores into plasticized poly(vinyl chloride) (PVC) membranes, which were directly coated on the surface of graphite electrodes. These novel electrodes display high selectivity for salicylate with respect to many common inorganic and organic anions. The influence of membrane composition and pH and the effect of lipophilic cationic and anionic additives on the response properties of the electrodes were investigated. The electrode based on aluminum salophen, with 32% PVC, 65.8% plasticizer, and 2.2% ionophore, shows the best potentiometric response characteristics and displays a linear log [Sal-] vs EMF response over the concentration range 1 x 10(-6) - 1 x 10(-1) M in phosphate buffer solutions of pH 7.0, with a Nernstian slope of -59.2 mV/decade of salicylate concentration. Highest selectivity was observed for the membrane incorporating 38.8% PVC, 57.3% plasticizer, 2.6% Sn(salophen), and 1.3% sodium tetraphenylborate. The electrodes exhibit fast response times and micromolar detection limits (approximately 1 x 10(-6) M salicylate) and could be used over a wide pH range of 3-8. Applications of the electrodes for determination of salicylate in pharmaceutical preparations and biological samples are reported.     

Advanced prospects for the preparation of zirconium [<Superscript>99</Superscript>Mo]molybdate(VI) gel from diluted reactants and <Superscript>99<Emphasis Type="Italic">m</Emphasis> </Superscript>Tc elution performance

Zirconium [⁹⁹Mo]molybdate(VI) gel (ZrMo) was prepared from dilute mixed solutions of zirconium oxychloride and [⁹⁹Mo]molybdate at pH 4.7. Paramolybdate(VI) anions were attracted to the positively charged surface of zirconia(IV) particulates (PZC at pH 7.2). The postulated reaction mechanism and gel formula were verified by radiometric analysis, X-ray diffraction, scanning electron microscopy, TGA, DTA, IR spectroscopy, and X-ray fluorescence analysis. ^99mTc elution from ZrMo dried at 50 and 200°C was investigated. Reproducibly high ^99mTc elution yield with high levels of radionuclidic, radiochemical, and chemical purity was achieved from the gel dried at 50°C. Correlation between structural properties of ZrMo and ^99mTc elution performance was discussed.     

Effect of Zr (IV) doping on the optical properties of sol–gel based nanostructured indium oxide films on glass

Zr (IV) doped indium oxide thin films (55 nm) were deposited onto pure silica glass by the sol–gel dip coating technique utilizing the precursors of 6 wt% equivalent oxide content. Three different Zr (IV) oxide (ZrO₂) dopant concentrations (5.0, 10.0 and 15.0 wt% w.r.t. total oxides) were chosen. XRD patterns suggested the films were of distinct cubic symmetry of In₂O₃. Nanostructured surface feature was revealed by FESEM images. Average cluster size decreased with increasing dopant concentration as evidenced from TEM study. Blue shift of band gap and UV cut off wavelength (lambda-50) occurred with increase in dopant concentration. The refractive index gradually increased with doping. Baking atmosphere plays an important role in tailoring the refractive index (RI) of the films and relatively high RI was obtained in the case of baking in pure oxygen. Presence of both free and bound excitons was detected by the photoluminescence (PL) study. The 5 wt% doped film exhibited relatively high PL intensity at 380 nm responsible for free exciton. The PL emissions gradually quenched with increase in dopant concentration. Similar behaviour was also observed when the film was baked in pure oxygen atmosphere.     

The synergistic inhibition effect of rare earth cerium(IV) ion and iso-vanillin on the corrosion of cold rolled steel in 1.0 M H2SO4 solution

The synergistic inhibition effect of rare earth cerium(IV) ion and iso-vanillin (3-hydroxy-4-methoxy-benzaldehyde) on the corrosion of cold rolled steel (CRS) in 1.0 M H₂SO₄ solution was first investigated by weight loss and potentiodynamic polarization methods. The results revealed that iso-vanillin had a moderate inhibitive effect on the corrosion of CRS in 1.0 M H₂SO₄ solution, while cerium(IV) ion had a negligible effect. However, incorporation of Ce⁴⁺ with iso-vanillin significantly improved the inhibition performance. The inhibition efficiency for Ce⁴⁺ in combination with iso-vanillin was higher than the summation of inhibition efficiency for single Ce⁴⁺ and single iso-vanillin, which was synergism in nature.     

P(MMA-MAh)凝胶聚合物电解质的制备及其性能

以自制的甲基丙烯酸甲酯与马来酸酐的共聚物(P(MMA-MAh))为基体,丙烯碳酸酯(PC)为增塑剂,LiClO4为锂盐,制备成凝胶聚合物电解质(GPE);采用交流阻抗法、差示扫描量热法(DSC)、热失重分析(TGA)对此GPE的电性能及热性能作了研究,并且研究了不同配比及温度对其离子电导率的影响.结果表明,以P(MMA-MAh)为基体的GPE与PMMA基GPE相比,共聚型P(MMA-MAh)的凝胶体系较好的成膜性和热稳定性;当共聚物含量为60%(质量分数)时,凝胶体系的玻璃化转变温度为27.28℃,质量损失为5%时热分解温度为145℃;当共聚物含量为45%(质量分数)时,凝胶聚合物电解质的综合性能较好;且共聚物P(MMA-MAh)基GPE的离子电导率与温度的关系服从Arrhenius方程.     

Ionic conductivity of a gel polymer electrolyte based on Mg(ClO4)2 and polyacrylonitrile (PAN)

Magnesium ion containing gel polymer electrolytes based on polyacrylonitrile (PAN) have been synthesized and characterized using ac impedance measurements. The electrolyte composition having the highest room temperature conductivity was found by varying the ratios propylene carbonate/ethylene carbonate (PC/EC) and PAN/Mg(ClO₄)₂. The corresponding composition was 18 mol% PAN:64 mol% EC:14 mol% PC:4 mol% Mg(ClO₄)₂. The ac conductivity measurements were carried out from room temperature upto 70 °C with blocking (stainless steel) electrodes. The room temperature conductivity is 3.2×10⁻³ S cm⁻¹ and the activation energy is 0.24 eV over the temperature range used. The high conductivity and the low activation energy of the material could possibly be due to the liquid electrolyte, Mg(ClO₄)₂ in EC/PC trapped in a matrix of PAN, as suggested by previous workers. According to dc polarization measurements, the gel electrolyte appears to be predominantly an anionic conductor.     

An optical chemical sensor for thorium (IV) determination based on thorin

A selective method for the determination of thorium (IV) using an optical sensor is described. The sensing membrane is prepared by immobilization of thorin–methyltrioctylammonium ion pair on triacetylcellulose polymer. The sensor produced a linear response for thorium (IV) concentration in the range of 6.46 × 10^?6 to 9.91 × 10^?5 mol L^?1 with detection limit of 1.85 × 10^?6 mol L^?1. The regeneration of optode was accomplished completely at a short time (less than 20 s) with 0.1 mol L^?1 of oxalate ion solution. The relative standard deviation for ten replicate measurements of 2.15 × 10^?5 and 8.62 × 10^?5 mol L^?1 of thorium was 2.71 and 1.65%, respectively. The optode membrane exhibits good selectivity for thorium (IV) over several other ionic species and are comparable to those obtained in case of spectrophotometric determination of thorium using thorin in solution. A good agreement with the ICP-MS and spiked method was achieved when the proposed optode was applied to the determination of thorium (IV) in dust and water samples.     

Synthesis and photocatalytic properties of nanomaterials based on titanium(IV) and zinc(II) oxides

We have synthesized materials based on titanium(IV) and zinc(II) oxides, containing 1 to 60 wt % Zn, at heat-treatment temperatures from 80 to 1150°C, with the formation of multiphase compositions (X-ray amorphous phase, anatase, rutile, ZnTiO₃, and/or Zn₂TiO₄) and studied their phase transitions, morphology, and photocatalytic activity. Increasing the Zn content of the materials is favorable for their spectral sensitization, including the range λ ≥ 670 nm.     

Destruction of organic pollutants by cerium(IV) MEO process: a study on the influence of process conditions for EDTA mineralization

The mediated electrochemical oxidation (MEO) process with cerium(IV) and nitric acid as the oxidizing medium was employed for the destruction of various model organic pollutants in continuous organic feeding mode. A near complete destruction was observed for all the organics studied. The effects of various experimental conditions were evaluated with respect to EDTA mineralization. The key parameters varied in the process were concentration of EDTA (67–268 mM), temperature (70, 80 and 95 °C), concentrations of Ce(IV) (0.7, 0.8 and 0.95 M), nitric acid (2, 3 and 4 M) and duration of organic addition (30 and 120 min). Under the experimental conditions of 80 °C and 0.95 M Ce(IV) in 3 M nitric acid, nearly 90% destruction was achieved based on CO₂ production and 95% based on TOC analyses for all the organic compounds studied. The in situ regeneration of mediator ion by the electrochemical cell was found to be good during the organic destruction within the range of experimental conditions studied. In the case of long term organic feeding (120 min) the destruction was calculated after the CO₂ evolution attained the steady state and under this condition the destruction efficiency was found to be 85% based on CO₂ evolution.