Production of Ac-225 from Th-229 for targeted alpha therapy

This work describes a method for the separation and purification of Ac-225 from a Th-229 source. The procedure is based on the combination of ion exchange and extraction chromatographic methods in nitric acid media and allows the preparation of carrier-free, clinical grade Ac-225 with an overall yield exceeding 95%. Quality control of the product is performed using radiometric (alpha, gamma spectrometry) and mass spectrometric methods. The Ac-225 product can be loaded on a radionuclide generator for the preparation of Bi-213 for preclinical and clinical studies of targeted alpha therapy of cancer and infectious diseases.     

Dissolution behaviour of 238U, 234U and 230Th deposited on filters from personal dosemeters

Kinetics of dissolution of (238)U, (234)U and (230)Th dust deposited on filters from personal alpha dosemeters was studied by means of a 26-d in vitro dissolution test with a serum ultrafiltrate simulant. Dosemeters had been used by miners at the uranium mine 'Dolní Rozínka' at Rozná, Czech Republic. The sampling flow-rate as declared by the producer is 4 l h(-1) and the sampling period is typically 1 month. Studied filters contained 125 +/- 6 mBq (238)U in equilibrium with (234)U and (230)Th; no (232)Th series nuclides were found. Half-time of rapid dissolution of 1.4 d for (238)U and (234)U and slow dissolution half-times of 173 and 116 d were found for (238)U and (234)U, respectively. No detectable dissolution of (230)Th was found.     

Separation and measurement techniques for the determination of 228Th, 230Th and 232Th in various matrices

Three analytical techniques are presented which are used at PSI for determination of U and Th isotopes (234U, 235U, 238U, 228Th, 230Th, 232Th) in different materials, i.e. environmental samples (soils, minerals) and dental ceramics as well as in urine for in vitro monitoring of potentially exposed workers. Depending on the sample quantity available and/or required detection limits the measurements are performed either directly via gamma spectrometry or via alpha particle counting with preceding separation chemistry. The separation methods applied are based on either extraction chromatography or on sorption of U and Th on actinide selective resin. Following sample digestion, chemical yield spike additions (232U, 225Th or 225Th), chemical purification and electro-depositional source preparation, alpha particle measurement is carried out using low-level alpha spectrometry. This technique allows detection limits of less than 0.2 mBq per counting source if the assay lasts over a few days and is therefore suitable for determination of trace quantities of short-lived 225Th that can be hardly detected by means of mass spectrometric techniques.     

Production of 225Ac and 223Ra by irradiation of Th with accelerated protons

The possibility of producing ²²⁵Ac and ²²³Ra by irradiation of natural ²³²Th with medium-energy protons was examined. Thorium foils were irradiated with 90-, 110-, and 135-MeV protons at the accelerator of the Institute for Nuclear Research, Russian Academy of Sciences, in Troitsk (Moscow oblast). The cumulative production cross sections for ²²⁵Ac were 6.7 ± 0.9, 9.8 ± 1.9, and 13.9 ± 1.5 mb, and for ²²⁷Th (²²³Ra precursor), 43 ± 5, 37 ± 6, and 35 ± 4 mb, respectively. Based on the experimental data and theoretical calculations, the possible yields of ²²⁵Ac and ²²³Ra in irradiation of thick thorium targets at various accelerators were determined. An efficient procedure was suggested for isolating the products from the irradiated targets: ²²⁵Ac, by liquid extraction and extraction chromatography, and ²²³Ra, by sublimation from a thorium-lanthanum melt followed by thermochromatographic separation in metallic titanium columns and extraction-chromatographic isolation of radium. The procedure allows production of large (units of curies) amounts of radiochemically pure ²²⁵Ac and ²²³Ra, which is promising for wide use of these radionuclides in nuclear medicine.     

Determination of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb concentration in excreta samples of inhabitants of a high natural background area

The high concentration of uranium and thorium in certain Brazilian areas provides an opportunity to evaluate the radiation exposure due to intake of radionuclides by the populations that live and work in areas with a high natural radiation background. Buena, where this study was conducted, is a small village on the coast in the northern part of Rio de Janeiro State, characterised by the presence of a large deposit of monazite sand. In this paper, the concentrations of 238U, 234U, 232Th, 228Th, 228Ra, 226Ra and 210Pb in faecal samples from inhabitants of this area were determined by a sequential analytical method. The results of the average concentrations in faeces of inhabitants of Buena are 9.4 +/- 3.4 mBq g(ash)(-1) for 238U, 9.2 +/- 4.0 mBq g(ash)(-1) for 234U, 7.0 +/- 4.2 mBq g(ash)(-1) for 232Th, 256.1 +/- 134.6 mBq g(ash)(-1) for 228Th, 335.5 +/- 192.8 mBq g(ash)(-1) for 228Ra, 156.6 +/- 74.1 mBq g(ash)(-1) for 226Ra and 66.7 +/- 17.7 mBq g(ash)(-1) for 210Pb. The results were compared with background concentrations from faecal samples from individuals living in Rio de Janeiro City. For most of the radionuclides analysed, the average concentration in faeces from inhabitants of the high natural radiation background was higher than the concentration found in Rio de Janeiro, considered a 'normal' background area.     

Investigations for InAs/GaAs multilayered quantum-dot structure treated by high energy proton irradiation

This paper focuses on the high energy proton irradiation effect of InAs/GaAs multilayers quantum-dot (QD) wafer and photodetector. With high energy proton path simulation, the releases of proton energy and trap distribution in QD multilayers are predicted well. Treated by 1 and 3 MeV protons, all protons almost penetrate the multilayers of QD structures and stop deeply in GaAs substrate. InAs QD multilayer structures/Infrared photodetector have been irradiated by protons with different energies (1 and 3 MeV) and doses (1 × 10⁹∼ 1 × 10¹³ protons/cm²). The photoluminescence (PL) and photoresponsivity (PR) spectrum of samples were measured and discussed with as grown and post irradiation.     

可控合成空心多孔氧化硅纳米管/CuS体系应用于化疗-光热靶向治疗

多功能药物载体的设计合成并应用于肿瘤的联合治疗得到了研究人员的广泛关注.本文介绍了一种连接靶向基团的化疗-光热联合治疗纳米平台.首先制备了尺寸可控的平均长度为40、55和150 nm的空心多孔氧化硅纳米管,在表面修饰具有光热功能的硫化铜纳米颗粒,然后连接乳糖酸基团实现肝癌细胞靶向功能.平均长度为40 nm、修饰靶向基团的空心多孔材料显示出良好的生物相容性,且具有最大的HepG2细胞吞噬量.负载盐酸阿霉素的纳米复合材料表现出pH和808 nm近红外激光刺激响应的释放效果.将CuS光热治疗和盐酸阿霉素化疗相结合的方法在体外和体内的抑制肿瘤效果都优于单独治疗.研究结果表明,该纳米复合材料在化疗-光热联合治疗方面具有潜在的应用价值.     

Determination of specific activity of 226Ra, 232Th and 40K for assessment of environmental hazards

Studies have been carried out using gamma-spectrometric techniques to determine the natural radioactivity in some rocks that are used as building materials in Yemen. The concentrations of the natural radionuclides namely(226) Ra, (232)Th and (40)K in the rock samples collected from different rock markets in Yemen have been determined using an NaI(Tl) detector. The concentrations of (226)Ra, (232)Th and (40)K in the studied rock samples range from 22.2 to 88.8 Bq kg(-1), 8.12 to 113.68 Bq kg(-1) and 31.3 to 2222.3 Bq kg(-1), respectively. The concentrations of these radionuclides are compared with the typical world values. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the air absorbed dose rate, the annual effective dose rate, the representative level index and the values of both external and internal hazard indices were evaluated and compared with the internationally approved values. The radium equivalent activity values of all rock samples are lower than the limit of 370 Bq kg(-1) except for one sample which is about 413.386. The values of external hazard index (H(ex)) and internal hazard index (H(in)), absorbed doses in indoor air and the corresponding effective dose equivalents in a typical dwelling are presented. The need for further studies is also discussed.     

Effects of proton irradiation on glass filter substrates for the Rosetta mission

The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) instrument on board the Rosetta spacecraft, a misson of the European Space Agency to comet P/Wirtanen, includes two cameras for acquiring images of the comet. A set of interference filters deposited upon glass and fused-silica substrates will be added to the cameras for wavelength tuning. For this mission of more than 10/years in an interplanetary environment, the requirement of preserving the optical characteristics of the filters is a critical one. We checked the variation in the transmission of some filter substrates after proton irradiation that simulated the solar wind. To produce a situation that is representative of the interplanetary environment, we irradiated proton fluences at three energies: 1.5 x 10(11) protons/cm2 at 4 MeV, 1.9 x 10(10) protons/cm2 at 8 MeV, and 7.1 x 10(9) protons/cm2 at 18 MeV. Seven substrates were tested: three Suprasil-1; three colored glasses, namely, OG590, KG3, and RG9; and one quartz. In addition, two interference filters were checked. The results obtained show that Suprasil-1 is rather insensitive to this irradiation, whereas very small reductions in transmission, of the order of a few percent, occur for colored glasses. The transmission of these filters was remeasured 2 years after the irradiation, and showed a general decrease in the transmission reduction.     

A facile method for preparing 3D graphene/Ag aerogel via gamma-ray irradiation

In this article, we report a simple method to fabricate graphene and Ag nanoparticles (NPs) composite aerogel (GA/Ag). The GO and Ag ions were in situ reduced by gamma-ray irradiation and went through self-assembly three-dimensional (3D) honeycomb-like porous composite aerogel in the presence of isopropanol. Measurements using XRD, XPS, SEM, TEM revealed that the GO and Ag ions can efficiently reduction into rGO and Ag NPs. In addition, Ag NPs were homogeneously attached to the graphene nanosheets of the honeycomb-like porous structure and had a typical diameter of 30–70 nm. Thus the gamma-ray irradiation-induced synthesis is an efficient method for preparing 3D GA/Ag composite.     

Conditions for dissolution and radiochemical isolation of U and Th from baddeleyite

Conditions of baddeleyite dissolution were examined, and an optimal method of its complete breakdown was found. A solution of ²²⁹Th tracer was prepared and used for radiochemical isolation of Th from baddeleyite. Radiochemical methds were developed for recovering the uranium and thorium fractions from a baddeleyite solution. The total chemical yield of U and Th was 71 ± 5 and 89 ± 7%, respectively.     

Monte Carlo dosimetry for targeted irradiation of individual cells using a microbeam facility

Microbeam facilities provide a unique opportunity to investigatethe effects of ionising radiation on living biological cellswith a precise control of the delivered dose. This paper describesdosimetry calculations performed at the single-cell level inthe microbeam irradiation facility available at the Centre d'EtudesNucléaires de Bordeaux-Gradignan in France, using theobject-oriented Geant4 Monte Carlo simulation toolkit. The cellgeometry model is based on high-resolution three-dimensionalvoxelised phantoms of a human keratinocyte (HaCaT) cell line.Such phantoms are built from confocal microscopy imaging andfrom ion beam chemical elemental analysis. Results are presentedfor single-cell irradiation with 3 MeV incident alpha particles.     

Preparation and catalytic activity of Pt/C materials via microwave irradiation

Microwave heating was employed to prepare highly dispersed Pt/C catalyst. Uniform platinum nanoparticles with average diameter of about 3.0-5.0 nm dispersed on carbon materials (XC-72) were synthesized using a domestic microwave oven. Synthesized Pt/C materials were characterized by X-ray diffraction and transmission electron microscopy. The particle size and size distribution of Pt nanoparticles greatly depend on microwave irradiation duration, where the heating temperature rises rapidly as the process proceeds. Cyclic voltammetry demonstrates that Pt/C catalysts derived from microwave irradiation for 90 s exhibits higher catalytic activity than a commercial Pt/C catalyst (E-Tek) at room temperature. The improvement in electrocatalytic activity of synthesized Pt/C materials is attributed to uniformity of particle size, well dispersion and high surface area, which is obtained around 175 °C and irradiation for 90 s.     

Catalysis stability enhancement of Fe/Co dual-atom site via phosphorus coordination for proton exchange membrane fuel cell

Non-precious metal catalysts(NPMCs)are promising low-cost alternatives of Pt/C for oxygen reduction reaction(ORR),which however suffer from serious stability ch...     

Vascular targeted single-walled carbon nanotubes for near-infrared light therapy of cancer

A new approach for targeting carbon nanotubes to the tumor vasculature was tested using human endothelial cells and MCF-7 breast cancer cells in vitro. Single-walled carbon nanotubes were functionalized with the F3 peptide using a polyethylene glycol linker to target nucleolin, a protein found on the surface of endothelial cells in the vasculature of solid tumors. Confocal microscopy and Raman analysis confirmed that the conjugate was internalized by actively dividing endothelial cells. Dividing endothelial cells were used to mimic these cells in the tumor vasculature. Incubation with the conjugate for 8?h or more caused significant cell death in both actively dividing endothelial cells and MCF-7 breast cancer cells, an effect that is hypothesized to be due to the massive uptake of the conjugate. This targeted cell killing was further enhanced when coupled with near-infrared laser treatment. For confluent (non-dividing) endothelial cells, no cytotoxic effect was seen for incubation alone or incubation coupled with laser treatment. These results are promising and warrant further studies using this conjugate for cancer treatment in vivo.     

250t/d转鼓碎浆机安装工艺

转鼓碎浆机设备体积质量大、安装精度要求高。文章结合设备安装过程，比较详细地介绍了该类设备的安装工艺。     

Empirical model estimation of relative biological effectiveness for proton beam therapy

A simple model for proton relative biological effectiveness (RBE) is proposed. It describes the RBE as a function of proton depth, the dose and the linear energy transfer (LET) when proton passes through tissue-like materials. Radiobiological parameters were first obtained by fitting the published experimental cell survival data. The dose-averaged LET values were calculated for 250-MeV proton beam in a water phantom by using GEANT4 Monte Carlo simulation code and were then used as input values to calculate the values of RBE as function of depths. The model was also applied to proton spread-out Bragg peak, where the increasing RBE with depth causes an extended RBE-weighted dose in the distal fall-off region. This model was found to be able to reproduce the measured RBE values as a function of LET, depth and dose for a specific cell line.     

The use of myristic acid as a ligand of polyethylenimine/DNA nanoparticles for targeted gene therapy of glioblastoma

To establish a gene delivery system for brain targeting, a low molecular weight polyethylenimine (PEI(10?K)) was modified with myristic acid (MC), and complexed with DNA, yielding MC-PEI(10?K)/DNA nanoparticles successfully. The nanoparticles were observed to be successfully taken up by the brains of mice. The transfection efficiency of the nanoparticles was then investigated, and both the in?vitro and in?vivo gene expression of MC-PEI(10?K)/DNA nanoparticles is significantly higher than that of unmodified PEI(10?K)/DNA nanoparticles. The anti-glioblastoma effect of MC-PEI(10?K)/pORF-hTRAIL was demonstrated by the survival time of intracranial U87 glioblastoma-bearing mice. The median survival time of the MC-PEI(10?K)/pORF-hTRAIL group (28 days) was significantly longer than that of the PEI(10?K)/pORF-hTRAIL group (24 days), the MC-PEI(10?K)/pGL(3) group (21 days) and the saline group (22 days). Therefore, our results suggested that MC-PEI(10?K) could be potentially used for brain-targeted gene delivery and in the treatment of glioblastoma.     

Synthesis of homogeneous PVP-capped SnS2 submicron particles via microwave irradiation

Homogeneous PVP-capped tin disulfide (SnS₂) submicron particles with narrow size distribution of ca. 300–500 nm have been successfully synthesized via microwave irradiation for 10 min for the first time. The samples were characterized using X-ray diffraction (XRD) and transmission electron microscope (TEM). In contrast, SnS₂ particles without PVP obtained under the same condition have irregular morphology. The experimental result indicated that PVP played an important role in controlling the shape and size distribution of particles, and in reducing the agglomeration degree of SnS₂ particles. The mechanism of PVPs improving the well dispersion of SnS₂ particles was discussed. The influence of solvent on the crystallinity of the as-prepared particles under microwave irradiation was primarily investigated.     

Calibration factors for determination of relativistic particle induced fission rates in U, U, Th, Pb and Au foils

Calibration factors w, for determination of fission rate in metallic foils of ^natU, ²³⁵U, ²³²Th, ^natPb and ¹⁹⁷Au were determined for foils in contact with synthetic mica track detectors. Proton-induced fission at proton energies of 0.7 GeV and 1.5 GeV were used. Using our experimental results as well as those of the other authors, w for different foil-mica systems were determined. Two methods were used to calculate w, relative to the calibration factor for uranium-mica system, which has been obtained in a standard neutron field of energy 14.7 MeV. One of these methods requires the knowledge of the mean range of the fission fragments in the foils of interest and other method needs information on the values of the fission cross-sections at the required energies as well as the density of the tracks recorded in the track detectors in contact with the foil surfaces. The obtained w-values were compared with Monte Carlo calculations and good agreements were found. It is shown that a calibration factor obtained at low energy neutron induced fissions in uranium isotopes deviates only by less than 10% from those obtained at relativistic proton induced fissions.