Radiochemical and biological characterization of <Superscript>99<Emphasis Type="Italic">m</Emphasis></Superscript>Tc-oxiracetam as a model for brain imaging

^99mTc-oxiracetam was prepared. It can be used as a radiotracer for brain imaging. Under the optimum conditions (0.5 mg of oxiracetam, 50 μg of SnCl₂·2H₂O, pH 7, room temperature, 30 min), the radio-chemical yield determined by chromatographic methods reached 96%. Biodistribution studies with mice showed that the brain uptake of the complex was 5.1% injected dose per gram (% ID/g) at 5 min post injection. In this parameter, the complex surpasses the commercially available ^99mTc-ECD (4.7% ID/g) and ^99mTc-HMPAO (2.25% ID/g).     

Synthesis of <Superscript>99<Emphasis Type="Italic">m</Emphasis></Superscript>Tc-Radiolabeled Uridine as a Potential Tumor Imaging Agent

Uridine, a pyrimidine nucleoside essential for the synthesis of RNA and biomembranes, was radiolabeled with ^99mTc to obtain a potential tumor imaging agent. The maximal radiochemical yield of about 96.5%, as determined by paper chromatography and instant thin-layer chromatography, was reached under the following optimum conditions: 1 mg of uridine, 20 μg of SnCl₂·2H₂O as reducing agent, 20 mg of mannitol as a stabilizer, and pH 8. ^99mTc-uridine is stable in vitro at room temperature for up to 6 h post labeling. The biodistrbution study in tumor-bearing mice shows high target-to-nontarget ratio. These results match with the high docking score of the complex on uridine phosphorylase enzyme. ^99mTc-uridine shows promise as a tumor imaging agent.     

Radiolabeling,quality control,and biodistribution of <Superscript>99m</Superscript>Tc-sulfadiazine as an infection imaging agent

Abstract—Sulfadiazine (antibiotic used for treating bacterial infections) was labeled with ^99mTc with the aim of the development of a new radiopharmaceutical for infection imaging. The influence of the reaction parameters such as the substrate and SnCl₂·2H₂O concentrations, pH of the reaction mixture, and reaction time on the labeling yield was examined, and the labeling conditions were optimized. The maximum radiochemical yield of ^99mTc-sulfadiazine (94.7%) was obtained by using 50 µg of SnCl₂·2H₂O and 1 mg of sulfadiazine at pH 5. The radiochemical purity of the labeled compound was evaluated by ITLC and HPLC. The biological distribution of ^99mTc-sulfadiazine in mice with experimentally induced Staphylococcus aureus infection in the right thigh was studied, and the bacterial infected thigh/normal thigh (target-to-nontarget, T/NT) ratio was evaluated. The T/NT ratio for ^99mTc-sulfadiazine was found to be 3.6, which is comparable to the commercially available ^99mTc-ciprofloxacin (3.8), indicating that ^99mTc-sulfadiazine can be used for infection imaging.     

Behavior of Microamounts of <Superscript>22</Superscript>Na, <Superscript>85</Superscript>Sr, <Superscript>137</Superscript>Cs,and <Superscript>152</Superscript>Eu in Sorption and Coprecipitation on Mixed Potassium Neodymium Ferrocyanide from Solutions

Sorption of ⁸⁵Sr, ¹³⁷Cs, ²²Na, and ¹⁵²Eu on solid mixed potassium neodymium ferrocyanide KNd[Fe(CN)₆]·4H₂O from neutral, acidic, and alkaline media and also coprecipitation of these radionuclides with KNd[Fe(CN)₆]·4H₂O in its formation from a homogeneous solution were studied. It was found that ⁸⁵Sr and ²²Na do not noticeably coprecipitate with solid KNd[Fe(CN)₆]·4H₂O and are not sorbed by this substance. In aqueous medium, depending on the cesium concentration in solution, from 80 to 98% of ¹³⁷Cs coprecipitates with solid KNd[Fe(CN)₆]·4H₂O. In this case, the distribution coefficient K_d depends on both the cesium concentration in solution and solution pH. Within 30 min of contact of the solid and liquid phases, the degree of recovery of ¹³⁷Cs from aqueous solution with KNd[Fe(CN)₆]·4H₂O is approximately 95.0% of the initial amount. ¹⁵²Eu coprecipitates with solid KNd[Fe(CN)₆]·4H₂O during its formation from a homogeneous solution to 98–99.9%. The degree of recovery of ¹⁵²Eu from aqueous solution with KNd[Fe(CN)₆]·4H₂O precipitate within 60 min of contact of the solid and liquid phases is 70.3% of the initial amount.     

Synthesis,Characterization, and Radiolabeling of Heterocyclic Bisphosphonate Derivative as a Potential Agent for Bone Imaging

1-Hydroxy-2-(2-pyridyl)ethanedisphosphonic acid monosodium salt (HPEDP) was prepared and labeled with ^99mTc using two different reducing agents: SnCl₂·2H₂O and NaBH₄; NaBH₄ gave better results. The radiochemical purity of ^99mTc(NaBH₄)-HPEDP was 96 ± 4%, and the complex was stable in vitro for 6 h. The in vivo biodistribution studies performed in mice show highly selective uptake of the labeled compound in the skeletal system and rapid elimination via the urinary pathway. The maximum bone uptake was 32.3 ± 2.1% ID/organ.     

Radiodiagnosis of peptic ulcer with technetium-99<Emphasis Type="Italic">m</Emphasis>-labeled esomeprazole

Esomeprazole was labeled with ^99m Tc in high (up to ~98.0%) radiochemical yield. The optimum conditions are as follows: pH 8, 50 μg of SnCl₂·2H₂O, 30 min, and 2 mg of the substrate. The complex is stable for 8 h. The reaction mixture was separated by gel chromatography using such eluents as NaCl solution and, phosphate, citrate, and carbonate buffer solutions. Free ^99m TcO ₄ ^– and the complex were also efficiently separated by reversed-phase HPLC, paper chromatography, and electrophoreses. Intravenous biodistribution studies of ^99m Tc-esomeprazole complex showed high uptake in the stomach ulcer, reaching about 30.5% ID/g at 1 h post injection. Such a high ^99m Tc-esomeprazole uptake makes this agent promising for stomach ulcer imaging.     

Optimized chromatographic separation and biological evaluation of <Superscript>99<Emphasis Type="Italic">m</Emphasis> </Superscript>Tc-clarithromycin for infective inflammation diagnosis

Clarithromycin antibiotic was labeled with technetium-99m by adding ^99mTc to clarithromycin in the presence of SnCl₂·2H₂O. The radiochemical yield of ^99mTc-clarithromycin was determined by chromatographic methods. Gel chromatographic method was investigated for separation of the reaction mixture using different eluents including NaCl and phosphate, citrate, and carbonate buffer solutions. Also, free ^99mTcO₄^- and ^99mTc-clarithromycin were efficiently separated by reversed-phase HPLC on RP18 column. The maximum radiochemical yield reached 98 ± 0.2%. ^99mTc-clarithromycin is stable for 6 h. Biological distribution of ^99mTc-clarithromycin was studied for mice with the infection in the left thigh induced using Staphylococcus aureus. The target-to-nontarget (T/NT) ratio for ^99mTc-clarithromycin was found to be 7.33 ± 0.13 at 2 h after intravenous injection, with the subsequent gradual decline. This value is higher than that of commercially available ^99mTc-ciprofloxacin. The abscess to normal muscle ratio shows that ^99mTc-clarithromycin can be successfully used for infection imaging, allowing differentiation between bacterial infection and sterile inflammation.     

Quaternary co-electrodeposition of the Cu2ZnSnS4 films as potential solar cell absorbers

Cu₂ZnSnS₄ (CZTS) films are successfully prepared on Mo substrate by electrochemical epitaxial method. An electrolyte contains 0.124 M CuSO₄·5H₂O, 0.14 M ZnSO₄, 0.13 M SnCl₂·2H₂O, 0.16 M Na₂S₂O₃·5H₂O, 2.25 M NaOH, 1.36 M C₆H₅Na₃O₇, 1.00 M C₄H₆O₆. The equilibrium potential for quaternary co-electrodeposited solution is set at ?1.1 ～ ?1.20 V. The results show that elements are deposited in the following sequence: Cu/S/Zn/S/Cu/S/Sn/S…. The ternary and quaternary compounds are formed with the increasing temperature during annealing. Finally the CZTS film can be well formed at 550 °C. The resistivity of CZTS is about 5.6 × 10⁴ Ω cm.     

Sn<Superscript>4+</Superscript> and La<Superscript>3+</Superscript> co doped TiO<Subscript>2</Subscript> nanoparticles and their optical,photocatalytic and antibacterial properties under visible light

Sn⁴⁺ and La³⁺ co-doped TiO₂ photocatalytic material with nanoparticle structure have been successfully prepared using SnCl₂·2H₂O and La(NO₃)₃·6H₂O as precursors. Scanning electron microscopy, X-ray diffraction, transmission electron microscopy and UV–visible spectroscopy have been used to for the characterization of the morphology, crystal structure, particle size and optical properties of the samples. The photocatalytic properties of sample with various amount of La doped TiO₂ have been studied by photo degradation of methyl orange (MO) in water under visible light. XRD patterns showed both rutile and anatase phases for 5 mol% of Sn and 5–10 mol% of La. But anatase phase with a little rutile phase was formed for 5 mol%Sn and 10 mol%La. The prepared Sn and La co doped TiO₂ photo-catalyst showed optical absorption edge in the visible light area and exhibited excellent photo-catalytic ability for degradation of MO solution under visible irradiation. Antibacterial behavior towards E. coli was then studied under visible irradiation. The synthesized T-5%Sn-10%La powder exhibited superior antibacterial activity under visible irradiation compared to the pure TiO₂.     

Dielectric properties and relaxation of Bi<Subscript>0·5</Subscript>Na<Subscript>0·5</Subscript>TiO<Subscript>3</Subscript>-BaNb<Subscript>2</Subscript>O<Subscript>6</Subscript> lead-free ceramics

A new member of lead-free piezoelectric ceramics of the BNT-based group, (1 − x)Bi_0·5Na_0·5TiO_3−x BaNb₂O₆, was prepared by conventional solid state reaction and its dielectric properties and relaxation was investigated. X-ray diffraction showed that BaNb2O6 diffused into the lattice of Bi_0·5Na_0·5TiO₃ to form a solid solution with perovskite-type structure. A diffuse character was proved by the linear fitting of the modified Curie-Weiss law. The temperature dependence of dielectric constant at different frequencies revealed that the solid solution exhibited relaxor characteristics different from classic relaxor ferroelectrics. The samples with x = 0·002 and 0·006 exhibited obvious relaxor characteristics near the low temperature dielectric abnormal peak, T _f, and the samples with x = 0·010 and 0·014 exhibited obvious relaxor characteristics between room temperature and T _f. The mechanism of relaxor behaviour was also discussed according to the macro-domain to micro-domain transition theory.     

Photoluminescence properties and charge compensation investigations of novel orange-emitting Eu<Superscript>3+</Superscript> doped Na<Subscript>4</Subscript>Ca<Subscript>4</Subscript>(Si<Subscript>6</Subscript>O<Subscript>18</Subscript>) phosphors

A series of polycrystalline Na₄Ca₄(Si₆O₁₈):Eu³⁺ orange emitting phosphors were synthesized by a conventional high-temperature solid-state reaction. The phase formation was confirmed by X-ray power diffraction analysis. The excitation spectra show a strong host absorption indicating an efficient energy transfer process from O^2? to Eu³⁺ ions. Upon NUV radiation, the phosphors showed strong red emission around 610 nm (⁵D₀ → ⁷F₂) and orange emission around 591 nm (⁵D₀ → ⁷F₁), but the ⁵D_1,2,3 emission nearly can not be seen. Compared with the luminescence properties of Li⁺, Na⁺, and K⁺ co-doped samples, we deduced that Na⁺ ions probably prefer to dope into the intrinsic Na vacancies rather than Ca²⁺ ions vacancies in Na₄Ca₄(Si₆O₁₈) crystal. Thermal stability properties, quantum efficiency and chromaticity coordinates of the phosphors have been investigated for the potential application in white LEDs.     

A study on electrodeposited Zn<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Fe<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> alloys

Zn_1−x Fe _x alloys were electrochemically deposited on AISI 4140 steel substrates from sulfate bath. The bath was consisted of 40 g dm⁻³ ZnSO₄·7H₂O, 20–40 g dm⁻³ FeSO₄·7H₂O_, 25 g dm⁻³ Na₃C₆H₅O₇, and 16 g dm⁻³ H₃BO_3. The effect of bath composition on the electrical resistivity, the phase structure, and the corrosion behavior were investigated by the current–voltage measurements versus temperature, the X-ray diffraction (XRD) analysis, the atomic absorption spectrometry analysis, and the polarization measurements, respectively. Iron content was shown to strongly affect the structure, the electrical resistivity and the corrosion stability of Zn–Fe alloys.     

Formation of Li<Superscript>+</Superscript> superionic crystals from the Li<Subscript>2</Subscript>S–P<Subscript>2</Subscript>S<Subscript>5</Subscript> melt-quenched glasses

The 70Li₂S·30P₂S₅ (mol%) glass was prepared by the melt quenching method and the glass–ceramic electrolytes were obtained by heating the prepared glass over crystallization temperatures. The superionic metastable Li₇P₃S₁₁ crystal was formed by heating the glass in the temperature range from 280 and 360 °C. The conductivity of the glass–ceramics was enhanced by the precipitation and growth of the Li₇P₃S₁₁ crystal, and the highest conductivity of 4.1 × 10⁻³ S cm⁻¹ at room temperature was achieved in the glass–ceramic heated at 360 °C for 1 h. The Li₇P₃S₁₁ crystal changed into the thermodynamically stable phase such as the Li₄P₂S₆ crystal with further increasing heat treatment temperature and holding time, resulting in lowering conductivities of the glass–ceramics.     

Crystallization from high-temperature solutions in the Na<Subscript>2</Subscript>O-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>-P<Subscript>2</Subscript>O<Subscript>5</Subscript>-M<Superscript>VI</Superscript>O<Subscript>3</Subscript> (M = Mo,W) systems

We have studied the crystallization behavior of Na₂O-NaPO₃-M^VIO₃(M^VI = Mo, W) high-temperature solutions containing 15 mol % Bi₂O₃ in the pseudoquaternary systems Na₂O-Bi₂O₃-P₂O₅-M^VIO₃ and have established the conditions for the formation of Na₃Bi(PO₄)₂, high-temperature BiPO₄, NaBi(MoO₄)₂, Bi₂WO₆, and NaMoO₂PO₄. The compounds identified have been characterized by powder x-ray diffraction and IR spectroscopy.     

Doping of the perovskite M<Superscript>I</Superscript>M<Superscript>II</Superscript>O<Subscript>3</Subscript> with weighable amounts of Pu and Am

Matrices of the compositions 0.2La₂O₃·Al₂O₃ and 0.4La₂O₃·Fe₂O₃, containing weighable amounts of Pu (13 mg g^?1) and Am (0.336 mg g^?1), were prepared, and their leaching rates were studied. The leaching rates calculated from the surface area determined by low-temperature nitrogen adsorption (BET method) virtually coincide with those found previously for the matrices with tracer amounts of the radionuclides, which indicates that these parameters are intrinsic characteristics of the matrices. The leaching rates calculated from the geometric surface areas are considerably higher and depend on the material porosity and hence on the procedure of its synthesis. The rates of the matrix corrosion were calculated from the ¹⁴⁷Pm leaching rates. They show that the matrix will not disintegrate into small fragments for 100 thousand years even under the emergency conditions of repository flooding with water.     

Li-storage and cycling properties of spinel,CdFe<Subscript>2</Subscript>O<Subscript>4</Subscript>, as an anode for lithium ion batteries

Cadmium ferrite, CdFe₂O₄, is synthesized by urea combustion method followed by calcination at 900°C and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED) techniques. The Li-storage and cycling behaviour are examined by galvanostatic cycling, cyclic voltammetry (CV) and impedance spectroscopy in the voltage range, 0·005–3·0 V vs Li at room temperature. CdFe₂O₄ shows a first cycle reversible capacity of 870 (± 10) mAhg⁻¹ at 0·07C-rate, but the capacity degrades at 4 mAhg⁻¹ per cycle and retains only 680 (± 10) mAhg⁻¹ after 50 cycles. Heat-treated electrode of CdFe₂O₄ (300°C; 12 h, Ar) shows a significantly improved cycling performance under the above cycling conditions and a stable capacity of 810 (± 10) mAhg⁻¹ corresponding to 8·7 moles of Li per mole of CdFe₂O₄ (vs theoretical, 9·0 moles of Li) is maintained up to 60 cycles, with a coulombic efficiency, 96–98%. Rate capability of heat-treated CdFe₂O₄ is also good: reversible capacities of 650 (± 10) and 450 (± 10) mAhg⁻¹ at 0·5 C and 1·4 C (1 C = 840 mAg⁻¹) are observed, respectively. The reasons for the improved cycling performance are discussed. From the CV data in 2–15 cycles, the average discharge potential is measured to be ∼0·9 V, whereas the charge potential is ∼2·1 V. Based on the galvanostatic and CV data, ex situ-XRD, -TEM and -SAED studies, a reaction mechanism is proposed. The impedance parameters as a function of voltage during the 1st cycle have been evaluated and interpreted. Dedicated to Prof. C N R Rao on his 75th birthday, and his contributions to science for the past 56 years     

Synthesis and characterization of M<Subscript>3</Subscript>V<Subscript>2</Subscript>O<Subscript>8</Subscript> (M = Ca,Sr and Ba) by a solid-state metathesis approach

A solid-state metathesis approach initiated by microwave energy has been successfully applied for the synthesis of orthovanadates, M₃V₂O₈ (M = Ca, Sr, and Ba). The structural, vibrational, thermal, optical and chemical properties of synthesized powders are determined by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, magnetic property measurements and diffused reflectance spectra in the UV-VIS range. The direct bandgap of the synthesized materials was found to be 3·55 ± 0·2 eV, 3·75 ± 0·2 eV and 3·57 ± 0·2 eV for Ca₃V₂O₈, Sr₃V₂O₈ and Ba₃V₂O₈, respectively.     

Enhanced red-emitting phosphor Na<Subscript>2</Subscript>Ca<Subscript>3</Subscript>Si<Subscript>2</Subscript>O<Subscript>8</Subscript>:Eu<Superscript>3+</Superscript> by charge compensation

A series of novel red-emitting Na₂Ca_3???x Si₂O₈:xEu³⁺ phosphors were synthesized by solid state reactions. The phosphors can strongly absorb 395 nm light, and show red emission with a good color purity. The excitation and emission spectra properties of Na₂Ca₃Si₂O₈:Eu³⁺ were characterized. Na₂Ca₃Si₂O₈:Eu³⁺ with self-compensated and alkali metal ions charge compensated approaches (2Ca²⁺→Eu³⁺ + M⁺, M?=?Li⁺, Na⁺, K⁺) have investigated, which found that the red emission of luminescent intensity can be greatly enhanced, and shows superior luminescent property to the commercial Y₂0₃S:Eu³⁺. The present work implies that the efficient charge compensated phosphors are promising candidates as red-emitting phosphor for w-LEDs.     

Growth and properties of LiCu<Subscript>2</Subscript>O<Subscript>2</Subscript>-NaCu<Subscript>2</Subscript>O<Subscript>2</Subscript> crystals

Platelike Li_{1 ? x} Na _x Cu₂O₂ single crystals up to 2 × 10 × 10 mm in dimensions have been grown by slowly cooling (1 ? x)Li₂CO₃·xNa₂O₂·4CuO melts in alundum crucibles in air. Li_{1 ? x} Na _x Cu₂O₂ solid solutions in the LiCu₂O₂-NaCu₂O₂ system have been shown to exist in the composition range 0.78 < x < 1. The temperature stability ranges of NaCu₂O₂ and LiCu₂O₂ are 780–930 and 890–1050°C, respectively. The Mössbauer spectra and electrical conductivity of the crystals have been measured.     

Ceramics Based on Powder Mixtures Containing Calcium Hydrogen Phosphates and Sodium Salts (Na<Subscript>2</Subscript>CO<Subscript>3</Subscript>, Na<Subscript>4</Subscript>P<Subscript>2</Subscript>O<Subscript>7</Subscript>, and NaPO<Subscript>3</Subscript>)

Ceramic materials in the Na₂O–CaO–P₂O₅ system have been produced using powder mixtures containing calcium hydrogen phosphates (monetite/brushite: CaHPO₄/CaHPO₄ ? 2H₂O) and sodium salts (Na₂CO₃ ? H₂O, Na₄P₂O₇ ? 10H,O, and NaPO₃). These salts were used as precursors to the following high-temperature phases: Сa₂P₂O₇, Na₂O, Na₄P₂O₇, and NaPO₃. The amount of the salts in the powder mixtures was such that the oxide composition of the ceramics corresponded to 10 mol % sodium oxide for each mixture in the Na₂O–CaO–P₂O₅ system. The powder mixtures were prepared using mechanical activation in acetone, which was accompanied by monetite rehydration to brushite. X-ray diffraction characterization showed that, after firing, the phase composition of the ceramics produced from the powder mixtures thus prepared lay in the Сa₂P₂O₇–NaCaPO₄–Na₂СaP₂O₇–Са(РО₃)₂ phase field. The resultant ceramic materials contain biocompatible and bioresorbable phases and can be recommended for bone implant fabrication.