Extraction and separation of141Ce and153Gd with HDEHP

Studies on liquid-liquid extraction of trace level cerium and gadolinium,¹⁴¹Ce and¹⁵³Gd, from HCl and HNO₃ media with liquid cation exchanger, HDEHP reveal that a quantitative separation of the elements from an admixture of the two radioisotopes can be achieved with 0.1% HDEHP and 0.01N HCl. The condition is also valid for separation of trace amount of¹⁵³Gd from bulk or macro quantity of cerium.     

(α, xn) reactions on natural samarium

A stack of natural samarium was bombarded with 87 MeV alpha particles. Cumulative cross sections for the production of¹⁵³Gd,¹⁵¹Gd,¹⁴⁹Gd,¹⁴⁷Gd,¹⁴⁶Gd have been studied using gamma-ray spectroscopy.     

Neutron activation R-matrix elements and κ-matrix elements and neutron energy spectra

In the present paper, the principle of using some -matrix elementsK _ij, such as¹⁷⁵Yb (i or j)-¹⁶⁹Yb (j or i),¹⁵³Gd (i or j)-¹⁵⁹Gd (j or i),¹⁰³Ru (i or j)-⁹⁷Ru (j or i) and⁹⁵Zr (i or j)-⁹⁷Zr (j or i), as neutron energy spectra monitors or indicators is discussed in detail. Some expoerimental results showed the tendency of change ofK _kj withK _ij of¹⁶⁹Yb (i)-¹⁷⁵Yb (j) and the ratios of infinitely dilute resonance integrals S_i, S_j and S_k to the respective thermal neutron capture cross-sections, where k represents nuclides other then i and j.     

The decay of153Gd

The sum peak method has been applied to calculate electron capture probability changes to 97 keV and 103 keV levels in the decay of¹⁵³Gd in different environments, e.g., HClO₄ and HNO₃. The relative and absolute intensities of KX-rays and -rays have been measured using a HPGe detector. In addition to these, electron capture intensities and electron capture decay energies (Q _Ec) have also been calculated.     

Synthesis and study of rare-earth uranogermanates

A series of M^III(HGeUO₆)₃ · 8H₂O rare-earth uranogermanates (M^III = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er) were prepared by precipitation from solutions under hydrothermal conditions. The compositions and structures of the synthesized compounds were studied, their complete crystallographic and functional similarity were established, and the processes of their dehydration and thermal decomposition were studied on the basis of chemical analysis, X-ray diffraction, IR spectroscopy, and differential scanning calorimetry data.     

Preparation of samarium-153-EDTMP and determination of its radiochemical purity using paper chromatography

Samarium-153-ethylenediaminetetramethylenephosphonate (¹⁵³Sm-EDTMP) has been used to palliate pain resulting from bone cancer. This paper describes the preparation of¹⁵³SmCl₃ from irradiated natural samarium and the ability of¹⁵³Sm to complex with EDTMP in liquid and in freeze-dried forms. The evaluation of radiolabeled EDTMP was done by paper chromatography. A rapid evaluation of free¹⁵³SmCl₃ and¹⁵³Sm-EDTMP was developed using a miniaturized chromatographic system.     

111In–L–LDL and 153Gd–L–LDL as radiotracers for detection of AR4‐2J rat pancreatic tumors

Pancreatic cancer has an extremely poor prognosis, due, in part, to lack of methods for early diagnosis. The present study was designed to evaluate the potential of labeling low‐density lipoprotein (LDL) with a radionuclide using a lipid chelating agent, bis(stearylamide) of diethylenetriaminepentaacetic acid (L), to detect pancreatic tumors by gamma‐scintigraphy. Previous studies indicated that the difficulty of visualization of pancreatic tumors was due to their poor vascularization. This study compares the ability of two radiotracers, ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL to target highly vascularized rat pancreatic tumors (AR4‐2J) implanted in nude mice. Biodistribution studies showed that the tumor uptake of ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL tracers was twofold and fivefold higher respectively than with the controls (¹¹¹In citrate and ¹⁵³Gd citrate respectively). These tracers would thus be suitable for scintigraphic imaging. We show here that LDL could be employed as a delivery system for tracers such as ¹¹¹In or ¹⁵³Gd when these two radionuclides are complexed by a lipid‐chelating anchor, and that ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL enabled better visualization of the pancreatic tumor tissues, with a better result with ¹⁵³Gd–L–LDL. Copyright © 2004 John Wiley & Sons, Ltd.     

Self-shielding and burn-out effects in the irradiation of strongly-neutron-absorbing material

Self-shielding and burn-out effects are discussed in the evaluation of radioisotopes formed by neutron irradiation of a strongly-neutron-absorbing material. A method of the evaluation of such effects is developed both for thermal and epithermal neutrons. Results of the calculation are discussed in comparison with the observed yields of¹⁵³Gd,¹⁶⁰Tb, and¹⁶¹Tb for the case of neutron irradiation of disc-shaped targets of gadolinium oxide.     

X-ray gated Mössbauer spectroscopic studies on57Co-labelled cobalt/II/ fluoride

KX-ray-gated emission Mössbauer spectra of⁵⁷Co-labelled CoF₂ and CoF₂.2H₂O were measured at room temperature, using the coincidence technique. A difference was found in the relative intensity of⁵⁷Fe(II)/⁵⁷Fe(III) between the X-ray-gated and non-gated emission spectra. The results are explained in terms of local radiolytic effects of water of crystallization and the chemical effects associated with the de-excitation processes caused by EC-decay.     

153Sm metallic-hydroxide macroaggregates: An improved preparation for radiation synovectomy

A new type of preparation employing¹⁵³Sm metallic-hydroxide macroaggregates (¹⁵³Sm-MHM) for radiation synovectomy was developed. The radiopharmaceutical was prepared by reacting the aqueous solution of¹⁵³SmCl₃ with sodium borohydride solution in 0.5N NaOH. Microscopic analysis showed that¹⁵³Sm-MHM mean particle size was 4 m (range 1–15 m) avoiding the formation of fine particles (<1 m) which were¹⁵³Sm-hydroxide macroaggregates preparations (¹⁵³Sm-HM). Also, suspension properties as sedimentation rate, were better for¹⁵³Sm-MHM than for¹⁵³Sm-hydroxyapatite and¹⁵³Sm-HM. Biological studies in normal rabbits demonstrated high retention into de Knee joint space even at 48 h after administration of¹⁵³Sm-MHM (>99%).     

Extraction chromatographic separation of carrier-free Tb and Pm generated in (p,xn)-type nuclear reactions

The nuclear reactions of (p, xn)-type, E_p=100–120 MeV, on Gd and Nd have been used to produce highly radioactive preparations of Tb and Pm enriched with neutron-deficient isotopes. Under comparable conditions the yields of practically all isotopes are considerably higher than in Tb and Gd spallation reactions at E_p=660 MeV. The radioactivity of screened¹⁵⁴Tb and¹⁵⁶Tb isotopes has been increased more than 40 times. Tb and Pm were separated from gram amounts of the target-elements by the extraction chromatography technique with undiluted di-(2-ethylhexyl) phosphoric acid as stationary phase. The radiochemical method developed was also applied to separate the radiochemically pure preparation of¹⁶¹Tb from Gd oxide irradiated with thermal neutrons.     

X-ray imaging of newly-developed gadolinium compound/silica core–shell particles

A preparation method for gadolinium compound (Gd) nanoparticles coated with silica (Gd/SiO₂) is proposed. Gd nanoparticles were prepared with a homogeneous precipitation method at 80 °C using 1.0 × 10⁻³ M Gd(NO₃)₃ and 0.5 M urea in the presence of 1.0 g/L stabilizer. Among stabilizers examined. Sodium n-dodecyl sulfate (SDS) was suitable as the stabilizer for preparing small Gd nanoparticles, and consequently Gd nanoparticles with a size of 46.2 ± 12.4 nm were prepared using the SDS. Silica-coating of the Gd nanoparticles was performed by a St?ber method at room temperature using 0.013 M TEOS and 2.0 × 10⁻³ M NaOH in water/1-propanol solution in the presence of 1.0 × 10⁻³ M Gd nanoparticles, which resulted in production of Gd/SiO₂ particles with an average size of 64.2 ± 14.4 nm. The Gd/SiO₂ particles were surface-modified with 3-aminopropyltrimethoxysilane and succinic anhydride. It was confirmed by measurement of electrophretic light scattering that amino group or carboxyl group was introduced onto the Gd/SiO₂ particles. The gadolinium concentration of 1.0 × 10⁻³ M in the as-prepared colloid solution was increased up to a gadolinium concentration of 0.4 M by centrifugation. The core–shell structure of Gd/SiO₂ particles was undamaged, and the colloid solution was still colloidally stable, even after the concentrating process. The concentrated Gd/SiO₂ colloid solution showed an X-ray image with contrast as high as a commercial Gd complex contrast agent. Internal organs in a mouse could be imaged injecting the concentrated colloid solution into it.     

Gadolinium(III) Porpholactones as Efficient and Robust Singlet Oxygen Photosensitizers

Construction of Gd^III photosensitizers is important for designing theranostic agents owing to the unique properties arising from seven unpaired f electrons of the Gd³⁺ ion. Combining these with the advantages of porpholactones with tunable NIR absorption, we herein report the synthesis of Gd^III complexes Gd‐1 – 4 ( 1 , porphyrin; 2 , porpholactone; 3 and 4 , cis‐ and trans‐porphodilactone, respectively) and investigated their function as singlet oxygen (¹O₂) photosensitizers. These Gd complexes displayed ¹O₂ quantum yields (Φ_Δs) from 0.64–0.99 with the order Gd‐1 < Gd‐2 < Gd‐3 < Gd‐4 . The gradually enhanced ¹O₂ sensitization after β‐oxazolone moiety replacement was ascribed to the narrowing of the energy gap (ΔE) between the lowest triplet states (T₁) of the ligand and the energy level of the ¹Δ_g→³Σ_g transition of ¹O₂. In particular, Gd‐4 is capable of excitation in the visible to NIR region (400–700 nm) with a quantum yield near unity. These Gd complexes were first demonstrated as efficient photosensitizers in photocatalysis such as oxidative C?H bond functionalization of secondary or tertiary amines, and the oxygenation of the natural product cholesterol. Finally, after glycosylation, these water‐soluble Gd complexes showed potential applications in photodynamic therapy (PDT) in HeLa cells. This work revealed that Gd^III complexes of “bioinspired” β‐modified porpholactones are efficient NIR photosensitizers and form a chemical basis to construct appealing photocatalysts and theranostic agents based on lanthanides.     

Application of the emission-transmission method for overcoming matrix effects in non-dispersive x-ray fluorescence analysis

An emission-transmission method in X-ray fluorescence analysis, based on theoretical considerations, has been applied for eliminating matrix effects due to variations in the chemical composition of samples. The measurements have been carried out in so-called compact geometry, using¹⁵³Gd source of the primary radiation and a NaI(Tl) crystal (3″ in diameter, 2 mm thick). The element to be determined was antimony in a CaCO₃ matrix with various admixtures of CuO. A method of semitheoretical construction of nomograms has been introduced for the evaluation of the measurements. Six variants of the method are discussed, and a criterion permitting to find the most useful variant is given. The theoretical considerations have been confirmed by the experiments.     

Interaction of Cs+, Sr2+ and Gd3+ with humin

Humin is separated from a soil sample and characterized by elemental analysis, IR and potentiometric titration. These investigations indicated that humin displayed similar characteristics as humic acid. The sorption behavior of¹³⁷Cs,⁹⁰Sr and¹⁵³Gd with humin was investigated from aqueous solution. The results indicated that the sorption process follows the order: Gd³⁺≫Sr²⁺>Cs⁺. It was time dependent and increased with pH. The sorption in the presence of humic acid or EDTA showed that both form a metal-ligand complex and consequently decrease the % uptake.     

Study on analysis of153Sm-EDTMP stability in vitro and vivo by HPLC

The behavior of¹⁵³Sm-EDTMP in vitro and vivo is analyzed by the size exclusion HPLC. The experimental results show that EDTMP amounts have an obvious effect on the stability in vitro and uptake of¹⁵³Sm-EDTMP in the liver. HPLC analysis of urine sample indicates that¹⁵³Sm-EDTMP es excreted in the original form. The behavior in vivo of¹⁵³Sm-EDTMP containing 4 μg is similar to that of¹⁵³Sm-EDTMP containing 50 μg EDTMP at 1 h post-injection.     

Changes in the inner coordination sphere as the primary chemical act of excited Gd3+aq

Photoexcited Gd(OH₂)³⁺₈ frees two water molecules to give ^*Gd(OH₂)³⁺₆ in an entropy-controlled process (ΔS^O ～ 9.5 cal/mol deg, ΔH^O ～ 0.32 kcal/mol, ΔG^O ～ ?2.5 kcal/mol) and secondary excited-state processes. This inner-sphere change may be rationalised by different 4f-shell contraction and 5p-shell expansion in the lowest and excited levels of the 4f⁷ configuration.     

K-shell vacancies at swift sulphur ions in Gd host

Single and double K-vacancy fractions at sulphur ions inside Gd are measured for ion velocities between 7v ₀ and 14v ₀ (v ₀=c/137) using the probe layer technique. These measurements, in combination with the available transient field (TF) precession data at 8v ₀, yield the degree of polarizationp _1s =0.15(3) for such ions in polarized Gd host. This value is considerably smaller than the generally accepted value of 0.24 for light ions. The present results when considered along with the recently reported small values ofp _1s for³²S and⁴⁰Ar ions at a velocity ofZv ₀ in Gd suggestvelocity independence andZ dependence in the polarization transfer mechanism for TF.     

Kit preparation of153Sm-EDTMP and factors affecting radiochemical purity and stability

A fast kit method was developed for the production of¹⁵³Sm-EDTMP in two steps avoiding the use of nitric acid, evaporation and sterilization of the final solution by autoclave. Methods of analysis for the determination of chemical and radiochemical purity in the radiopharmaceutical solution were established. Factors affecting radiochemical purity and stability of the complex as the molar ratio of EDTMP/Sm, concentration of phosphate buffer and neutralization of EDTMP prior kit preparation were also analyzed. The use of this radiopharmaceutical in rabbits and patients showed selective skeletal uptake.     

Voltammetric determination of itopride using carbon paste electrode modified with Gd doped TiO2 nanotubes

In the present work TiO₂ nanotubes (TNT) have been synthesized by alkaline hydrothermal transformation. Then they have been doped with Gd element. Characterizations of doped and undoped TNT have been done with TEM and SEM. The chemical composition was analyzed by EDX, Raman and FTIR spectroscopy. The crystal structure was characterized by XRD. Carbon paste electrode has been fabricated and mixed with Gd doped and undoped TNT to form a nanocomposite working electrode. Comparison of bare carbon paste electrode and Gd doped and undoped TNT carbon paste electrode for 1.0 ×10⁻³ M K₄ [Fe(CN)₆] voltammetric analysis; it was observed that Gd doped TNT modified electrode has advantage of high sensitivity. Gd doped TNT modified electrode has been used as working electrode for itopride assay in a pharmaceutical formulation. Cyclic voltammetry analysis showed high correlation coefficient of 0.9973 for itopride (0.04–0.2 mg/mL) with a limit of detection (LOD) and limit of quantitation values (LOQ) of 2.9 and 23.0 μg.mL⁻¹ respectively.