Luminescence and photoionization of X-ray generated Sm2+ in coprecipitated CaF2 nanocrystals.

We report photoluminescence and photoionization properties of Sm2+ ions generated by X-irradiation of nanocrystalline CaF2:Sm3+ prepared by coprecipitation. The nanocrystals were of 46 nm average crystallite size with a distribution of ±20 nm and they were characterised by XRD, TEM and SEM-EDS. At room temperature, the X-irradiated sample displayed broad electric dipole allowed Sm2+ 4f55d (A1u) → 4f6 7F1 (T1g) luminescence at 725 nm that narrowed to an intense peak at 708 nm on cooling to ∼30 K. The narrow f-f transitions of Sm3+ were also observed. The X-irradiation-induced reduction of Sm3+ + e- → Sm2+ as a function of X-ray dose was investigated over a very wide dynamic range from 0.01 mGy to 850 Gy by monitoring the photoluminescence intensities of both Sm2+ and Sm3+ ions. The reverse Sm2+ → Sm3+ + e- photoionization can be modelled by employing dispersive first-order kinetics and using a standard gamma distribution function, yielding an average separation of 13 Å between the Sm2+ ions and the hole traps (e.g. oxide ion impurities). The present results point towards potential applications of Sm doped CaF2 nanocrystals in the fields of dosimetry and X-ray imaging.

Radium-223 for the treatment of bone metastases in castration-resistant prostate cancer: when and why.

Radium-223 dichloride (223Ra) is the first, recently approved, α-particle-emitting radiopharmaceutical for the treatment of patients with bone metastases in castration-resistant prostate cancer (CRPC) and no evidence of visceral metastases. We explored MEDLINE, relevant congresses, and websites for data on 223Ra and prostate cancer therapies, focusing on therapeutic strategies and timing, bone metastases, and diagnostic assessment. 223Ra represents the only bone-targeting agent that has significantly extended patients' overall survival while reducing pain and symptomatic skeletal events. Unlike other radiopharmaceuticals, such as strontium-89 and samarium-153 EDTMP, 223Ra (11.4-days half-life) has shown a high biological efficiency mainly due to its short penetration range. These features potentially allow reduced bone marrow toxicity and limit undue exposure. 223Ra has been validated under the product name Xofigo® by the US Food and Drug Administration and the European Medicines Agency. Patient selection, management, and treatment sequencing is recommended to be discussed in the context of a multidisciplinary environment, including oncology, urology, nuclear medicine, and radiation therapy physicians. No consensus has been achieved regarding the optimal timing and its administration as single agent or in combination with zoledronic acid or chemotherapy, so far. This review aims to provide a rationale for the use of 223Ra in treating metastases from CRPC, highlighting the crucial role of a multidisciplinary approach, the disputed inclusion and exclusion criteria on the basis of agencies regulations, and the value of diagnostics for therapy assessment.

Microwave synthesis of pure and doped cerium (IV) oxide (CeO2) nanoparticles for methylene blue degradation.

Cerium (IV) oxide (CeO2), samarium (Sm) and gadolinium (Gd) doped CeO2 nanoparticles were prepared using microwave technique. The effect of microwave irradiation time, microwave power and pH of the starting solution on the structure and crystallite size were investigated. The prepared nanoparticles were characterized using X-ray diffraction, FT-Raman spectroscopy, and transmission electron microscope. The photocatalytic activity of the as-prepared CeO2, Sm and Gd doped CeO2 toward degradation of methylene blue (MB) dye was investigated under UV light irradiation. The effect of pH, the amount of catalyst and the dye concentration on the degradation extent were studied. The photocatalytic activity of CeO2 was kinetically enhanced by trivalent cation (Gd and Sm) doping. The results revealed that Gd doped CeO2 nanoparticles exhibit the best catalytic degradation activity on MB under UV irradiation. For clarifying the environmental safety of the by products produced from the degradation process, the pathways of MB degradation were followed using liquid chromatography/mass spectroscopy (LC/MS). The total organic carbon content measurements confirmed the results obtained by LC/MS. Compared to the same nanoparticles prepared by another method, it was found that Gd doped CeO2 prepared by hydrothermal process was able to mineralize MB dye completely under UV light irradiation.

Adsorption and enhanced photocatalytic activity of the {0 0 0 1} faceted Sm-doped ZnIn2S4 microspheres.

In this study, the doping effect of samarium on the structure, morphology, adsorption and photocatalytic performance of hexagonal ZnIn2S4 microspheres was studied. The photocatalytic activity of Sm-doped ZnIn2S4 microspheres was evaluated for the photodegradation of Rhodamine B (RhB) and methyl orange (MO) under visible light irradiation. The samples were characterized by XRD, SEM, XPS, UV-vis, TEM, and N2 adsorption-desorption analysis. The results show that the hexagonal ZnIn2S4 microspheres are composed of nanoplates growing along c-axis with the predominant negative-charged S plane. Compared with the photodegadation of MO dye, the negative-charged {0 0 0 1} facets not only are beneficial for the adsorption of RhB by -N(Et)2 groups but also can accumulate the separation of photogenerated electrons and holes, enhancing photodegradation efficiency by direct-hole photocatalysis. Moreover, Sm is partially substituted for In in the crystal lattice for forming the doping energy level which promotes the separation of photoinduced electron-hole pairs and enhances absorption of visible light. Hexagonal 2% Sm-doped ZnIn2S4 microspheres with exposed {0 0 0 1} facets resulted in higher photodegradation efficiency of RhB under visible light irradiation.

Thermoluminescence of terbium sensitised by samarium in CaF2.

Thermoluminescence (TL) in sintered CaF2 doped with Tb4O7 has been studied for UV and X-ray irradiation. Three TL glow peaks for the Tb4O7 doped sample appeared in the temperature regions of about (1) 347-353 K, (2) 378-383 K and (3) 453-458 K, when heated at a rate of 20 K min(-1) after UV or X-ray irradiation at room temperature. It has been found that the 378 K peak intensity of the samples co-doped with Tb4O7 and Sm2O3 became stronger when compared with those doped with only terbium or samarium ions, and the TL peaks of (1) 347-353 K and (3) 453-458 K were not observed. The intensity of the 378 K peak of the co-doped sample was 12.9 times that of the sample doped only with Tb4O7. From the TL spectra and the excitation and emission spectra of photoluminescence for the CaF2 doped activators, it is concluded that the TL of Tb3+ ions is sensitised by the existence of Sm3+ ions. The 378 K TL peak may also be suitable for UV radiation dosimetry.

Efeitos da braquiterapia intra-arterial com samário-153 sobre a neoproliferação intimal / Effects of intra-arterial brachytherapy with Samarium- 153 over intimal neoproliferation

Estudos experimentais e em humanos o balão de angioplastia pode levar à estenose pela migração e proliferação das células musculares lisas e a síntese de matriz extracelular. Estudos têm mostrado a ação da braquiterapia contra esses mecanismos. Nós desenhamos este estudo para avaliar a inibição do tecido de proliferação pelo Samário-153(153Sm). Quarenta e três coelhos hipercolesterolêmicos foram submetidos à lesão de ambas artérias ilíacas e separados em três grupos: com a dose de 15 Gy (n=14), com 60 Gy (n=36) e controle (n=36). A análise histológica morfométrica mostrou significante redução da neo-íntima com 15 Gy, quando comparado com os outros grupos. A dose de 60 Gy teve modificações estruturais e tissulares sugestivas de radiolesão.As previous demonstrated by experimental and human models, balloon dilation during angioplasty could lead to injury and stenosis due to smooth muscle cell migration and proliferation as well as extracellular matrix synthesis. Brachytherapy has been usefull against these factors. We pourposed was this study to evaluate neointimal tissue proliferation inhibition by Samarium-153 (153 Sm). Forty-three hypercholesterolemic rabbits underwent balloon injury in their both iliac arteries. They were separated into three groups: throught 15 Gy irradiation doses (n=14), 60 Gy (n=36) and control group (n= 36). Histopathologic and morphometric analysis showed a significant neointimal reduction with 15 Gy, comparing to others groups to control and 60 Gy dosis. The 60 y doses determined structure and tissue changes as the ones of radiation lesion...

Radionuclide production for therapeutic radiopharmaceuticals.

A fundamental task within the framework of a project searching for new radiopharmaceuticals for systemic therapy was the evaluation of the capabilities of the Portuguese Research Reactor (RPI) for the production of several important radionuclides. The feasibility of producing 64Cu, 77As, 153Sm, 165Dy, 166Ho, 170Tm, 177Lu, 186Re, 199Au and 111Ag in useful quantities was evaluated for the present RPI operation schedule (12 h cycles) and for continuous operation. The main evaluation criteria are expressed in terms of specific activity for continuous irradiation and/or 12 h cycle and the use of natural or enriched targets if necessary. Selected samples were irradiated and a comparison between measured activities and values calculated according to the irradiation schedule and using the same software was performed.

Thermoluminescence in sintered CaF2:Tb.

In order to observe and estimate the dose of ultraviolet (UV) radiation, the thermoluminescence (TL) of sintered CaF2 doped with Tb4O7 and Sm2O3 was studied. A several kind of lanthanides elements are doped in pure CaF2 powder crystals and properties of the TL to UV radiation were observed. The TL intensity from CaF2:Tb was the highest among the samples doped other lanthanide elements. The TL emission may be due to the recombination reaction; Tb2+ + hole-->Tb3+*-->Tb3+ + hv. The TL peaks are observed at about 353 K, 378 K and 458 K. It was found that the 378 K TL peak intensity of CaF2:Tb became strong by addition of Sm2O3. The 378 K TL peak may also be suitable for use as a dosimeter.