Phase diagram of the selenium–sulfur system in the pressure range 1 × 10<Superscript>–5</Superscript>–1 × 10<Superscript>–1</Superscript> MPa

The partial pressures of the components in the saturated vapor of the Se–S system were determined and presented as the temperature–concentration dependences. Based on these data, the boundaries of the melt–vapor phase transition at atmospheric pressure and in vacuum (1350, 100, and 10 Pa) were calculated. A complete phase diagram was constructed, which included the vapor–liquid equilibrium fields at atmospheric and low pressures, whose boundaries allowed us to determine the behavior of sulfur and selenium during distillation separation.     

Effect of F<Superscript>–</Superscript>-doping on the transport properties of perovskite-like complex oxides

The structural and electric characteristics of fluorine-substituted complex oxides obtained by anion doping based on Ba₂CaNbO_5.5 and Ba₂In₂O₅ matrices were compared. The mobility of ion charge carriers was found to depend on the concentration of the dopant anion and oxygen vacancies and the degree of disordering of the latter.     

Separation of phosphorous by liquid–liquid extraction for the measurement of <Superscript>32</Superscript>P

Phosphorous containing radioisotope waste was separated and determined by liquid–liquid extraction method through liquid scintillation counter (LSC). In this process, ammonium phosphate was converted to phosphomolybdate (PMo) by the reaction of ammonium molybdate (Mo) in HCl solution (0.02 M) and maximum UV/VIS absorbance (λ_max) 218 nm was observed. The PMo solution was extracted with TOA (Tri-n-Octylamine)/xylene mixture and λ_max 290 nm was found for this organic layer. Absorbance of aqueous and organic layer was linear through concentration. The impurities such as Co, Cr, Gd, etc. remain in aqueous layer by treating with Mo which was determined by ICP-AES and AAS. The quenching correction curve for ³²P was calculated using LSC results. No counting change was observed as the volume of quenchers increased. The recovery was 98% and 81% for the extraction and separation process from the test using H₃³²PO₄ as standard tracer.     

Study on the preparation and biological evaluation of <Superscript>99m</Superscript>Tc–gatifloxacin and <Superscript>99m</Superscript>Tc–cefepime complexes

The aim of this work is the development of new radiopharmaceuticals for imaging infection and inflammation in human. Gatifloxacin (fluoroquinolone derivative) and cefepime (cephalosporine derivative) are antibiotics used to treat bacterial infections were investigated to label with one of the most important radioactive isotopes (technetium-99m). The reaction parameters that affect the labeling yield such as substrate concentration, stannous chloride dihydrate concentration, pH of the reaction mixture, and reaction time were studied to optimize the labeling conditions. Maximum radiochemical yield of ^99mTc–gatifloxacin (90  ± 1.8%) complex was obtained by using 50 μg SnCl₂·2H₂O and 2.5 mg gatifloxacin at pH 10 while ^99mTc–cefepime was prepared at pH 8 with a maximum radiochemical yield of 98  ± 1.4% by adding ^99mTc to 5 mg cefepime in the presence of 50 μg SnCl₂·2H₂O. Biological distribution of ^99mTc–gatifloxacin and ^99mTc–cefepime was carried out in experimentally induced infection rats, in the left thigh, using Escherichia coli. Both thighs of the rats were dissected and counted and the ratio of bacterial infected thigh/contralateral thigh was then evaluated. T/NT for both ^99mTc–gatifloxacin and ^99mTc–cefepime was found to be 4.5  ± 0.3 and 8.4  ± 0.1, respectively, which was higher than that of the commercially available ^99mTc–ciprofloxacin. The abscess to normal muscle ratio indicated that ^99mTc–cefepime could be used for infection imaging. Besides, in vitro studies showed that ^99mTc–cefepime can differentiate between bacterial infection and sterile inflammation.     

Thermodynamics of the formation of Cu<Superscript>2+</Superscript>–glycyl-glycyl-glycine complex in water–ethanol solutions at 298 K

The stability constants of monoligand complexes of copper(II) ions with glycyl-glycyl-glycine zwitterions (triglycine, HL^±) and triglycinate ions (L^?) in a water–ethanol solvent with 0.0, 0.1, 0.3, and 0.5 mole fractions of ethanol at an ionic strength of 0.1 created by sodium perchlorate and temperature Т = 298.15 K are determined by means of potentiometric titration. It is found that an increase of ethanol content improves the stability of the investigated complexes, due mainly to the resolvation of ligands.     

Coordinatively Unsaturated Polynuclear Mixed-Valent Sn<Superscript>II</Superscript>–Sn<Superscript>IV</Superscript> and Cu<Superscript>II</Superscript>–Sn<Superscript>IV</Superscript> Oxo-Centered Carboxylates

The tetranuclear mixed-valent oxo-cluster [Sn^IISn^IVO(O₂CCF₃)₄]₂ (1) has been prepared by reacting SnCl₂ with AgO₂CCF₃ in a sealed ampoule at 90 °C. Alternatively, 1 was obtained by acidolysis of Ph₃SnSnPh₃ with trifluoroacetic acid in solution. The X-ray diffraction study of 1 revealed the presence of a Sn^IIOSn₂^IVOSn^II core comprised of the penta-coordinated divalent and six-coordinated tetravalent tin atoms. The ¹¹⁹Sn NMR studies confirmed the stability of the cluster in solution and the presence of two different oxidation states of tin. An acidolysis of Ph₃SnSnPh₃ in the presence of [Cu₂^II(O₂CCF₃)₄] followed by sublimation of the resulting product at 90 °C afforded the first trinuclear mixed metal Sn–Cu cluster [(C₆H₅)₂Sn₂^IVCu^IIO(O₂CCF₃)₆] (2). The X-ray diffraction analysis of 2 revealed the presence of two phenyl groups attached to the six-coordinated tin(IV) atoms and the tetragonal pyramidal environment of the copper(II) atom. Both complexes have been obtained free of exogenous ligands.     

Quantum chemical study of formation of Cu<Superscript>II</Superscript>–Y<Superscript>III</Superscript> metallamacrocyclic complexes based on glycinehydroximate ligands

The process of solution-phase formation of the Cu^II–Y^III 15-metallacrown-5 complexes bearing the glycinehydroximate ligands has been for the first time investigated by methods of quantum chemistry. The DFT modeling at the B3LYP/DGDZVP (PCM) level was carried out for mono-, bi-, and tri-nuclear copper(II) complexes and also for heteronuclear Cu^II–Y^III derivatives as the metallamacrocycle precursors. The dependence of relative stability of these complexes on the Cu^II and Y^III coordination surroundings and also on the mutual positions of ligands was found. The structural (variations of interatomic distances and valence angles), electronic (changes in the atomic charges and electron density), and thermodynamical (enthalpies and Gibbs free energies) regularities of 15-metallacrown-5 formation were revealed. The key role of Y^III cation was established for the process of formation of the polynuclear metallamacrocyclic compound (15-metallacrown-5).     

Theoretical evaluation of the radiative lifetimes of LiCs and NaCs in the A<Superscript>1</Superscript>Σ<Superscript>+</Superscript> state

Calculations of the adiabatic potential energy curves and the transition dipole moments between the ground (A¹Σ⁺) and the first excited (A¹Σ⁺) states have been determined for the LiCs and NaCs molecules. The calculations are performed using an ab initio approach based on non-empirical pseudopotentials for Cs⁺, Li⁺ and Na⁺ cores, parameterized l-dependent polarization potentials and full configuration interaction calculations. The potential energy curves and the transition dipole moment are used to estimate the radiative lifetimes of the vibrational levels of the A⁺Σ⁺ state using the Franck–Condon (FC) approximation and the approximate sum rule method. The radiative lifetimes associated with the A⁺Σ⁺ state are presented here for the first time. These data can help experimentalists to optimize photoassociative formation of ultracold molecules and their longevity in a trap or in an optical lattice.     

Experimental Determination of the Isotherm at 15°C of the System Mg<Superscript>2+</Superscript>/Cl<Superscript>−</Superscript>, SO<Subscript>4</Subscript><Superscript>2</Superscript>–H<Subscript>2</Subscript>O

Summary.  The diagram of the ternary system Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O was established at 15°C by means of analytical and conductimetric measurements. Three compounds were found in this diagram, which are MgSO₄·6H₂O, MgSO₄·7H₂O, and MgCl₂·6H₂O. The solubility field of MgSO₄·7H₂O is important whereas those of MgSO₄·6H₂O and MgCl₂·6H₂O are small. The compositions (mass-%) of the two invariant points determined by the two methods are: MgSO₄:MgCl₂=2.73:33.80 and MgSO₄: MgCl₂=3.38:28.91. Both the measured and the calculated isotherm at 15°C have been used for modelling of the diagram Mg²⁺/Cl⁻, SO₄ ²⁻–H₂O between 0 and 35°C. The polythermal invariant point was approximately located between 15 and 10°C.  Corresponding author. E-mail: ariguib@planet.tn Received October 16, 2002; accepted (revised) December 3, 2002 Published online April 24, 2003 RID="a" ID="a" Dedicated to Prof. Dr. Heinz Gamsj?ger on the occasion of his 70^th birthday     

Optimization of the labeling yield by determination of the Cu<Superscript>+</Superscript>–acetonitrile complex constant in Cu<Superscript>+</Superscript>-catalyzed nucleophilic exchange reactions in mixed solvent conditions

To apply the Cu⁺-assisted nucleophilic exchange based radioiodination of aromatic compounds for more lipophilic compounds the reaction is carried out in mixed solvent conditions. Due to its physicochemical properties acetonitrile is an attractive solvent. Although acetonitrile forms complexes with Cu⁺ decreasing the labeling yield. This article describes a method for the determination of the complex constant at labeling temperature based on a Lineweaver–Burk approach, relating the reaction rate constant and the concentration of precursor in presence of different amounts of acetonitrile. The method also allows to calculate the adjusted amount of copper salt in order to obtain the same high labeling yield as obtained in absence of acetonitrile.     

Preparation and bioevaluation of <Superscript>99m</Superscript>Tc–carbonyl complex of guanine

The aim of this study is to prepare radiolabeled guanine with ^99mTc(CO)₃⁺ core. For this purpose, guanine has been radiolabeled with ^99mTc(CO)₃⁺ core. Quality control study of radiolabeled guanine molecule with ^99mTc(CO)₃⁺ core was performed by thin layer radio chromatography (TLRC) and high performance liquid radio chromatography (HPLRC). The results showed that the radiolabeling yield was quite high (94 ± 3%). Beside that ^99mTc(CO)₃–Gua complex has showed good in vitro stability during the 24 h period. Radiopharmaceutical potential of this complex was evaluated in Wistar Albino Rats. It was concluded that ^99mTc(CO)₃–Gua could be used as a nucleotide radiopharmaceutical for in vivo applications.     

Relativistic coupled cluster calculations of the electronic structure of KrH<Superscript>+</Superscript>, XeH<Superscript>+</Superscript> and RnH<Superscript>+</Superscript>

Potential energy curves of NgH⁺ cations (Ng = Kr, Xe, Rn) were obtained by using four-component relativistic CCSD(T) coupled cluster calculations. Dissociation energies, equilibrium bond lengths, electronic properties, such as dipole moments and electric field gradients at the nuclei, and the related spectroscopic parameters of the electronic ground state have been determined. The results obtained for KrH⁺ and XeH⁺ are in good agreement with available experimental data, while those for RnH⁺ have been determined for the first time at this level of theory.     

Pulse radiolysis study of the oxidation of the I<Superscript>−</Superscript> ions with the radical anions Br<Subscript>2</Subscript><Superscript>·−</Superscript> in an aqueous solution: formation and properties of the radical anion BrI<Superscript>·−</Superscript>

The radiation chemical redox transformations in solutions of bromides in the presence of minor additives of iodides were studied by pulse radiolysis. The change in the concentrations of the Br⁻ and I⁻ ions changes the ratio of the formed short-lived radical anions Br₂ ^·−, BrI^·−, and I₂ ^·−. The spectrum of the mixed radical anion BrI^·− contains a broad optical band at 370 nm with ɛ₃₇₀ = 9650 L mol⁻¹ cm⁻¹. The reduction potential of the BrI^·−/Br⁻, I⁻ pair is 1.25 V. The rate constants for the forward and backward reactions Br₂ ^·− + I⁻ ⇌ BrI^·− + Br⁻ are k _f = 4.3·10⁹ and k _r = 1.0·10⁵ L mol⁻¹ s⁻¹, respectively; for the reactions BrI^·− ⇌ Br⁻ + I^·, k _f = 5.7·10⁸ s⁻¹ and k _r = 1.0·10¹⁰ L mol⁻¹ s⁻¹. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1787–1792, September, 2008.     

The effects of pretreatment of polycrystalline gold with OH<Superscript>•</Superscript> radicals on the electrochemical nucleation and growth of platinum

The nucleation and growth of platinum on polycrystalline gold was studied by chronoamperometry, cyclic voltammetry, and atomic force microscopy before and after treatment of the gold surface with hydroxyl (OH^•) radicals. Two different procedures of mechanical polishing of the gold surface (“coarse polish” and “fine polish”) were applied before the treatment with OH^• radicals. The nucleation and growth of Pt was much better reproducible on electrodes which underwent a “coarse polish”. The treatment of the Au surface with OH^• radicals decreased the number of active sites; however, the nucleation growth mode remained the same (3-D instantaneous). The spontaneous Pt deposition (no externally applied potential) on Au was unaffected by the treatment with OH^• radicals. In situ atomic force microscopy experiments showed that the Pt starts to grow only on some of the Au grains, most probably on those which have active sites on their surface. This leads to a roughening of the electrode surface upon Pt deposition. Treatment with OH^• radicals did only quantitatively diminish the amount of deposited Pt, but qualitatively the imaging of the Pt growth remained the same. Obviously, the OH^• radicals lead to a knockout (decreasing number) of active sites for Pt nucleation, while the nature of the remaining active sites stays unaffected.     

Studies on the porphine labeled with <Superscript>99m</Superscript>Tc–pertechnetate

The aim of this research is to use acetylacetonate as a ^99mTc chelating agent label with porphyrin and evaluate its radiochemical and biological characteristics. Stannous chloride was used as a reductant to determine the chemical and biological characterization of ^99mTc-complexes from labeling porphine{4′,4′′,4′′′-(2lH,23H-Porphine-5,10,15,20-terayl)tetrakis-(benzoic acid), TPPB} with ^99mTc–pertechnetate. Instant thin layer chromatography (ITLC), size exclusion chromatography (SEC), paper electrophoresis, and UV/Vis spectrophotometry were used to evaluate chemical characterization. Finally, biodistribution and liver function tests were applied to evaluate biological characteristics. The results of this study show that the labeling efficiency of ^99mTc(acac)–TPPB was nearly 100% when using acetylacetone (acac) as a conjugator. Three major ^99mTc(acac)–TPPB complexes were separated by SEC, and all of them were hydrophilic. The UV-Vis spectra of ^99mTc(acac)–TPPB complexes closely resembled those of the TPPB, but the wave lengths of their peaks changed 430, 521, 556, 591 and 647 nm after complexation. The biodistribution study selected the liver as the target organ. The ^99mTc(acac)–TPPB complex may cause short-term liver injury. However, this injury can be repaired, and the reagent is quickly metabolized. Hence, the toxicity of the ^99mTc(acac)–TPPB complex is within an acceptable range, and making it a promising liver imaging agent.     

Crystallinity of Dynasan<Superscript>®</Superscript>114 and Dynasan<Superscript>®</Superscript>118 matrices for the production of stable Miglyol<Superscript>®</Superscript>-loaded nanoparticles

This study focuses on the physicochemical characterization of lipid materials useful for the production of the so-called solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC). The chosen lipids were Dynasan^®114 (glyceril trimyristate) and Dynasan^®118 (glyceril tristearate) as solid lipids (SL), melting temperature above 80 °C, and Miglyol^®812 (caprylic/capric triglyceride) and Miglyol^®840 (propylene glycol dicaprylate/dicaprate) as liquid lipids (LL), crystallizing below ?15 °C. Raw lipids (pure or SL:LL mixtures) were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD), and Polarized Light Microscopy (PLM), before and after tempering at 80 °C for 1 h. The selected SL:LL combination was 70% (Dynasan^®114 and 118) and 30% (Miglyol^®812 and 840) for the production of SLN and NLC by high-pressure homogenization (HPH), respectively. Particles with a mean size of 200 nm (polydispersity index <0.329) and zeta potential of ?15 mV were obtained, and their long-term stability was confirmed for 3 months of storage at 7 °C.     

Study on the thermal behavior of the complexes of the type [PdX<Subscript>2</Subscript>(tdmPz)] (X = Cl<Superscript>−</Superscript>, Br<Superscript>−</Superscript>, I<Superscript>−</Superscript>, SCN<Superscript>−</Superscript>)

Four new mononuclear Pd(II) complexes of the type [PdX₂(tdmPz)] {X = Cl⁻ (1); Br⁻ (2); I⁻ (3); SCN⁻ (4); tdmPz = 1-thiocarbamoyl-3,5-dimethylpyrazole} have been synthesized and characterized by elemental analysis, IR spectroscopy, ¹H and ¹³C{¹H}-NMR experiments. The thermal behavior of the complexes 1–4 has been investigated by means of thermogravimetry (TG) and differential thermal analysis (DTA). From the initial decomposition temperatures, the thermal stability of the complexes can be ordered in the sequence: 3 < 4 ≡ 2 < 1. The final products of the thermal decompositions were characterized as metallic palladium by X-ray powder diffraction.     

The effect of NO<Stack><Subscript>3</Subscript><Superscript>−</Superscript></Stack> and OH<Superscript>−</Superscript> ions on the laser ablation of Cs<Superscript>+</Superscript> ion on Type 304 stainless steel

Type 304 stainless steel specimens artificially contaminated with CsCl solution were treated with KOH solution and KNO₃ solution, respectively. Cs⁺ ion removal tests by a Q-switched Nd:YAG laser at 1064 nm at a given fluence of 57.3 J/cm² were performed. The surface morphology and the relative atomic mole ratio of the specimen surface were investigated by SEM and EPMA. The order of Cs⁺ ion removal efficiency of laser was no-treatment < KOH < KNO₃ during the 42 shots. From the investigation of XPS peaks around 532.7 and 292.9 eV, KNO₃ on a surface of specimen was found to be fully decomposed during the laser irradiation. It was suggested that Cs₂O particulates formed by the reaction between the reactive oxygen generated from the nitrate ion and Cs⁺ ion on the metal surface could be easily suspended. For the KOH system, FeOOH was formed during the laser irradiation and it changed into Fe₂O₃. It was also suggested that Cs₂O particulates were formed by the reaction between the reactive oxygen generated from the decomposition of K₂O and Cs⁺ ion on the metal surface..     

Counterion effects on the isotopic properties of the Cl<Superscript>−</Superscript> and Li<Superscript>+</Superscript> ions in aqueous solutions

The reduced partition function ratios between isotopic forms (β-factors) were calculated by the ab initio RHF/6-311++G**(3df, 3p) and MP2/6-311++G**(3df, 3p) quantum-chemical methods for hydrated chloride ion and ion pair hydrates NaCl·nH₂O and LiOH · nH₂O. The influence of the Na⁺ cation on the β-factor value and the chlorine isotope separation factor in the precipitation of NaCl from concentrated aqueous solutions was found to be substantial. At the same time, the presence of OH^? counterions had no noticeable effect on the β-factor of the hydrated Li⁺ cation.