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1.
PLoS One ; 15(5): e0229452, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32357150

RESUMO

Most of South Africa's energy is derived from the combustion of coal in pulverized coal-fired power plants (CFPP). However, when compared with the rest of the world, limited information regarding the main radioactive elements (U and Th) and specific radionuclides of interest (K40, Ra226 and Th232) from South African CFPP is available in the public domain. This paper aims to quantify the U, Th and specific radionuclides found in the coal used in selected South African CFPP in comparison to world averages found in literature. The U and Th concentrations were obtained by ICP-MS. The main radionuclides, K40, Ra226 and Th238, were quantified using gamma spectrometry. The U concentration and Th concentrations for the coal used in all the power plants was above the world average of 1.9 mg/kg and 3.2 mg/kg respectively. The coals with the highest Th content originated from the Mpumalanga power plant, while the U content in the Freestate power plant samples was the highest of the three. The concentrations of the K40 were between 88.43±10.75-110.76±8.92 Bq/kg, which are in-line with world averages of 4-785 Bq/kg. Similarly, the Ra226 and Th232 values were between 21.69±2.83-52.63±4.04 Bq/kg and 19.91±1.24-22.97±1.75 Bq/kg respectively, which are also in line with the world averages of 1-206 Bq/kg and 1-170 Bq/kg respectively. Radiological hazard indices such as radium equivalent (Raeq); external hazard index (Hex) and internal hazard index (Hin), that were estimated from these average radionuclide concentrations were less than the prescribed values found in literature. This indicated that no significant health risk was posed by the coal being used from these coal fields.


Assuntos
Carvão Mineral/análise , Centrais Elétricas , Poluentes Radioativos do Solo/isolamento & purificação , Cinza de Carvão/análise , Humanos , Doses de Radiação , Monitoramento de Radiação , Radioisótopos/química , Radioisótopos/isolamento & purificação , Rádio (Elemento)/química , Rádio (Elemento)/isolamento & purificação , Poluentes Radioativos do Solo/química , África do Sul , Espectrometria gama , Tório/química , Tório/isolamento & purificação , Urânio/química , Urânio/isolamento & purificação
2.
Chemosphere ; 237: 124488, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31401427

RESUMO

The adsorptive capability of rice-husk for the sorption of thorium ions from aqueous solutions in batch mode was studied. The key process variables (initial metal ion concentration, initial solution pH and S/L (solid-to-liquid ratio) were optimized for achieving maximum bioremoval efficiency (B%) by employing the Box-Behnken design (33) in response surface methodology (RSM). A quadratic model developed by fitting the experimental data predicted 93% of the responses and estimated the local maximum of B% as >99% for an initial ThIV concentration of 150  g/L, S/L ratio of 5, and an initial pH of 4, and the reported biosorption capacity (qe) is 15.95 mg/g for the same conditions. Freundlich isotherm (R2 = 0.9841) and pseudo-first-order (R2 = 0.9416) kinetic models had the best concurrence with the experimental data in the thorium concentration range used implying the sorption mechanism involves surface biosorption and intraparticle diffusion.


Assuntos
Tório/química , Poluentes Químicos da Água/química , Adsorção , Difusão , Concentração de Íons de Hidrogênio , Cinética , Metais , Oryza , Soluções , Tório/análise , Água , Poluentes Químicos da Água/análise
3.
Biosens Bioelectron ; 141: 111420, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31220726

RESUMO

Recently, nanomaterial-based artificial enzymes have expected abundant consideration because of cheap, accessibility, and respectable stability. In this study, we report a Th-MOF artificial peroxidase, which can oxidize 3,3,5,5-tetramethylbenzidine by hydrogen peroxide to yield a blue product. The catalytic behavior of Th-MOF tracked Michaelis-Menten equation and the affinity of this nanozyme to the substrate was higher than horseradish peroxidase as a natural enzyme. The absorbance value of oxidized TMB is linearly associated with the hydrogen peroxide concentration. Since, hydrogen peroxide is the oxidative end product of uric acid (UA) by uricase, an efficient and sensitive approach for uric acid determination was also established. Results showed that Km value of Th-MOF with TMB as a substrate is much lower than that of other mentioned catalysts. The linear regression equations for uric acid substrate was stated as A = 0.0039C + 0.0519 with a correlation coefficient of 0.9955. The linear range for uric acid was from 4.0 to 70 µM, and the LOD was measured as 1.15 µM. Furthermore the absorbance of assay reaction was approximately constant in the following four cycles, demonstrating that Th-MOF catalyst has outstanding stability. Results showed that the public interfering substances had no obvious absorbance values and it was less than 0.1. Results indicated that the recoveries for UA in serum fluids were between 93.10% and 99.04%. The relative standard deviation (RSD, n = 3) at each concentration value was less than 4.3%. UA determination in serum fluids has been confirmed through a comparison between the recommended technique and tedious clinical approaches. Good recovery and accuracy of UA measurement indicated that this established colorimetric sensing system is appropriate for UA revealing in actual experimental samples.


Assuntos
Estruturas Metalorgânicas/química , Tório/química , Urato Oxidase/química , Ácido Úrico/sangue , Ácido Úrico/urina , Benzidinas/química , Materiais Biomiméticos/química , Técnicas Biossensoriais/métodos , Candida/enzimologia , Catálise/efeitos dos fármacos , Colorimetria/métodos , Humanos , Peróxido de Hidrogênio/química , Modelos Moleculares , Oxirredução , Peroxidase/química
4.
Molecules ; 24(10)2019 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-31109077

RESUMO

Actinium-225 (225Ac) can be produced with a linear accelerator by proton irradiation of a thorium (Th) target, but the Th also underdoes fission and produces 400 other radioisotopes. No research exists on optimization of the cation step for the purification. The research herein examines the optimization of the cation exchange step for the purification of 225Ac. The following variables were tested: pH of load solution (1.5-4.6); rinse steps with various concentrations of HCl, HNO3, H2SO4, and combinations of HCl and HNO3; various thorium chelators to block retention; MP50 and AG50 resins; and retention of 20-45 elements with different rinse sequences. The research indicated that HCl removes more isotopes earlier than HNO3, but that some elements, such as barium and radium, could be eluted with ≥2.5 M HNO3. The optimal pH of the load solution was 1.5-2.0, and the optimized rinse sequence was five bed volumes (BV) of 1 M citric acid pH 2.0, 3 BV of water, 3 BV of 2 M HNO3, 6 BV of 2.5 M HNO3 and 20 BV of 6 M HNO3. The sequence recovered >90% of 225Ac with minimal 223Ra and thorium present.


Assuntos
Actínio/química , Cátions/química , Cromatografia por Troca Iônica , Metais/química , Rádio (Elemento)/química , Tório/química , Ácidos/química , Quelantes/química , Concentração de Íons de Hidrogênio
5.
Molecules ; 24(6)2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30897722

RESUMO

During the purification of radioisotopes, decay periods or time dependent purification steps may be required to achieve a certain level of radiopurity in the final product. Actinum-225 (Ac-225), Silver-111 (Ag-111), Astatine-211 (At-211), Ruthenium-105 (Ru-105), and Rhodium-105 (Rh-105) are produced in a high energy proton irradiated thorium target. Experimentally measured cross sections, along with MCNP6-generated cross sections, were used to determine the quantities of Ac-225, Ag-111, At-211, Ru-105, Rh-105, and other co-produced radioactive impurities produced in a proton irradiated thorium target at Brookhaven Linac Isotope Producer (BLIP). Ac-225 and Ag-111 can be produced with high radiopurity by the proton irradiation of a thorium target at BLIP.


Assuntos
Actínio/química , Tório/química , Astato/química , Prótons , Radioisótopos/química , Ródio/química , Prata/química
6.
Environ Pollut ; 248: 82-89, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30780070

RESUMO

One of the most important reasons for the controversy over the development of nuclear energy is the proper disposal of spent fuel. Separation of actinide and lanthanide ions is an important part of safe long-term storage of radioactive waste. Herein, a three-dimensional (3D) graphene-based macrostructure (GOCS) was utilized to remove actinide thorium and lanthanide europium ions from aqueous solutions. The adsorption of Eu(III) and Th(IV) on the GOCS was evaluated as a function of adsorption time, solution pH, initial ion concentrations, and ionic strength. The experimentally determined maximum adsorption capacities of this GOCS for Eu(III) (pH 6.0) and Th(IV) (pH 3.0) are as high as 150 and 220 mg/g, respectively. By using Fourier transformation infrared (FT-IR), X-ray photoelectron (XPS), and extended X-ray absorption fine structure (EXAFS) spectroscopy, we concluded that the Eu(III) and Th(IV) adsorption was predominantly attributed to the inner-sphere coordination with various oxygen- and nitrogen-containing functional groups on GOCS surfaces. Our selective adsorption results demonstrate that the actinide and lanthanide ions can be effectively separated from transition metal ions. This study provides new clues to the overall recycling of actinide and lanthanide ions in radioactive environmental pollution treatments.


Assuntos
Quitosana/química , Recuperação e Remediação Ambiental/métodos , Európio/química , Grafite/química , Resíduos Radioativos/análise , Tório/química , Adsorção , Concentração de Íons de Hidrogênio , Centrais Nucleares , Concentração Osmolar , Espectroscopia de Infravermelho com Transformada de Fourier , Espectroscopia por Absorção de Raios X
7.
Environ Sci Pollut Res Int ; 26(3): 2523-2530, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30471065

RESUMO

In order to remove aqueous radionuclides and find an appropriate method for the disposal of wild duckweed in eutrophic water body, alkali-treated duckweed biomass and duckweed-based hydrothermal biochar (hydrochar) and pyrolytic biochars of 300 and 600 °C were prepared. Their physicochemical properties were characterized carefully. The adsorption isothermal data fitted well with the Langmuir model and the maximum Langmuir adsorption capacities were 104.1, 96.3, 86.7, and 63.5 mg/g for hydrochar, modified biomass, and 300 and 600 °C biochars, respectively. The adsorption kinetic data fitted well with the pseudo-second-order kinetic equation. The sorption data of fixed-bed column also confirmed the high efficient removal of Th(IV) and fitted well with the Thomas model. The duckweed-based hydrothermal biochar is a low-cost adsorbent for Th(IV) removal, and it is also a resource utilization technology of the duckweed collected from eutrophic water body.


Assuntos
Carvão Vegetal/química , Tório/química , Adsorção , Álcalis/química , Biomassa , Cinética , Pirólise , Poluentes Químicos da Água/análise , Purificação da Água/métodos
8.
Environ Sci Pollut Res Int ; 26(3): 3019-3032, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30506383

RESUMO

Intensive anthropogenic activities may add to pollution risks to lakes and rivers, which can be revealed by the magnetic characteristics of sediments. The present study aims to assess the pollution status of the sediment of a typical reservoir in northwestern China by application of magnetic susceptibility. The values of magnetic susceptibility exhibited significant positive correlations with trace metals (Co, Cu, Mn, Ni, and V) and natural radionuclides (232Th and 40K). Multivariate statistical analysis indicated common sources and similar deposition characteristics of magnetic particles and trace metals. It was conformed that magnetic susceptibility could be used as an indicator to identify industrial sources of trace metals, but was not suitable to indicate the traffic or natural sources. Linear regression equations between the low-frequency magnetic susceptibility and the integrated pollution index as well as annual effective dose rate indicated a potential for using magnetic susceptibility in semi-quantitative assessment of trace metal pollution and radiological hazard in sediments. A three-step procedure is proposed for the use of magnetic susceptibility in pollution monitoring, which provides a fast and effective method for estimating the pollution extent and tracing the major sources of trace metals in the sediment of lakes and rivers.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Poluição Química da Água/análise , China , Lagos , Modelos Lineares , Magnetismo , Metais/análise , Metais/química , Análise Multivariada , Radioisótopos de Potássio/análise , Tório/análise , Tório/química , Poluentes Químicos da Água/análise
9.
Inorg Chem ; 57(22): 14337-14346, 2018 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-30372069

RESUMO

The solution chemistry of a chelator developed for 227Th targeted alpha therapy was probed. The compound of interest is an octadentate ligand comprising four N-methyl-3-hydroxy-pyridine-2-one metal-binding units, two tertiary amine groups, and one carboxylate arm appended for bioconjugation. The seven p Ka values of the ligand and the stability constants of complexes formed with Th(IV), Hf(IV), Zr(IV), Gd(III), Eu(III), Al(III), and Fe(III) were determined. The ligand exhibits extreme thermodynamic selectivity toward tetravalent metal ions with a ca. 20 orders of magnitude difference between the formation constant of the Th(IV) species formed at physiological pH, namely [ThL]-, and that of its Eu(III) analogue. Likewise, log ß110 values of 41.7 ± 0.3 and 26.9 ± 0.3 (T = 25 °C) were measured for [ThL]- and [FeIIIL]2-, respectively, highlighting the high affinity and selectivity of the ligand for Th ions over potentially competing endogenous metals. Single crystal X-ray analysis of the Fe(III) complex revealed a dinuclear 2:2 metal:chelator complex crystallizing in the space group P1̅. The formation of this dimeric species is likely favored by several intramolecular hydrogen bonds and the protonation state of the chelator in acidic media. LIII edge EXAFS data on the Th(IV) complexes of both the ligand and a monoclonal antibody conjugate revealed the expected mononuclear 1:1 metal:chelator coordination environment. This was also confirmed by high resolution mass spectrometry. Finally, kinetic experiments demonstrated that labeling the bioconjugated ligand with Th(IV) could be achieved and completed after 1 h at room temperature, reinforcing the high suitability of this chelator for 227Th targeted alpha therapy.


Assuntos
Quelantes/química , Complexos de Coordenação/química , Piridonas/química , Compostos Radiofarmacêuticos/química , Tório/química , Anticorpos Monoclonais Humanizados/química , Cinética , Ligantes , Estrutura Molecular , Termodinâmica , Espectroscopia por Absorção de Raios X
10.
PLoS One ; 13(3): e0193659, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29509801

RESUMO

Low-cost biosorbents (ginkgo leaf, osmanthus leaf, banyan leaf, magnolia leaf, holly leaf, walnut shell, and grapefruit peel) were evaluated in the simultaneous removal of La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Yb3+, Lu3+, UO22+, Th4+, Y3+, Co2+, Zn2+, Ni2+, and Sr2+ from aqueous solutions. In single metal systems, all adsorbents exhibited good to excellent adsorption capacities toward lanthanides and actinides. In a simulated multicomponent mixed solution study, higher selectivity and efficiency were observed for Th4+ over other metal cations, with ginkgo leaves providing the highest adsorptivity (81.2%) among the seven biosorbents. Through optimization studies, the selectivity of Th4+ biosorption on ginkgo leaf was found to be highly pH-dependent, with optimum Th4+ removal observed at pH 4. Th4+ adsorption was found to proceed rapidly with an equilibrium time of 120 min and conform to pseudo-second-order kinetics. The Langmuir isotherm model best described Th4+ biosorption, with a maximum monolayer adsorption capacity of 103.8 mg g-1. Thermodynamic calculations indicated that Th4+ biosorption was spontaneous and endothermic. Furthermore, the physical and chemical properties of the adsorbent were determined by scanning electron microscopy, Brunauer-Emmett-Teller, X-ray powder diffraction, and Fourier transform infrared analysis. The biosorption of Th from a real sample (monazite mineral) was studied and an efficiency of 90.4% was achieved from nitric acid at pH 4 using ginkgo leaves.


Assuntos
Ginkgo biloba/química , Folhas de Planta/química , Tório/química , Água/química , Adsorção , Citrus paradisi/química , Simulação por Computador , Recuperação e Remediação Ambiental , Ficus/química , Concentração de Íons de Hidrogênio , Ilex/química , Juglans/química , Cinética , Magnolia/química , Modelos Teóricos , Ácido Nítrico/química , Oleaceae/química , Pós/química , Soluções/química , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Tório/isolamento & purificação , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Difração de Raios X
11.
Regul Toxicol Pharmacol ; 92: 245-250, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29277438

RESUMO

Black sand samples collected from Baltim beaches (Kafr El-Sheikh governorate) in Egypt on the Mediterranean Sea shore were analyzed radiometrically and evaluated using a nondestructive gamma ray spectroscopic techniques. The natural radionuclides of 226Ra, 232Th and 40K in the black sand samples were identified and quantified. It is found that the activity concentrations for 226Ra, 232Th and 40K in different eleven sites (S1S11) were found within the ranges of 28-322, 91-308 and 81-339 Bq/kg, respectively. Moreover, different radiological hazardous parameters (absorbed dose rate, annual effective dose equivalent, radium activity, annual gonadal dose equivalent and excess lifetime cancer risk) were calculated. The results show that these values are greater than the permissible values due to increasing the activity concentrations of the primordial radionuclides 226Ra, 232Th and 40K. The dose rate for radiation emitted at 1 m from the surface of land was measured directly and the results shown that all sites emit radiation doses more than the international permissible value (57 nGy/h) especially at three sites which around 340 nGy/h. These values are important to establish baseline levels of this environmental radioactivity to detect any upcoming change for the local population and resorts people. The relatively high dose rate will be considered as a spa for the physical therapy such as treatment of some skin diseases and rheumatoid.


Assuntos
Radioisótopos de Potássio/química , Monitoramento de Radiação/métodos , Radioisótopos/química , Rádio (Elemento)/química , Poluentes Radioativos do Solo/análise , Tório/química , Monitoramento Ambiental/métodos , Raios gama , Mar Mediterrâneo , Doses de Radiação , Radioatividade
12.
Anal Chim Acta ; 998: 75-82, 2018 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29153089

RESUMO

Column chromatographic methods have been developed to separate no-carrier-added 111Ag from proton irradiated thorium targets and associated fission products as an ancillary process to an existing 225Ac separation design. Herein we report the separation of 111Ag both prior and subsequent to 225Ac recovery using CL resin, a solvent impregnated resin (SIR) that carries an organic solution of alkyl phosphine sulfides (R3P = S) and alkyl phosphine oxides (R3P = O). The recovery yield of 111Ag was 93 ± 9% with a radiochemical purity of 99.9% (prior) and 87 ± 9% with a radiochemical purity of 99.9% (subsequent to) 225Ac recovery. Both processes were successfully performed with insignificant impacts on 225Ac yields or quality. Measured equilibrium distribution coefficients for silver and ruthenium (a residual contaminant) on CL resin in hydrochloric and nitric acid media are reported, to the best of our knowledge, for the first time. Additionally, measured cross sections for the production of 111Ag and 110mAg for the 232Th(p,f)110m,111Ag reactions are reported within.


Assuntos
Actínio/química , Prótons , Prata/isolamento & purificação , Nanomedicina Teranóstica , Tório/química , Prata/química , Espectrometria gama
13.
Mutagenesis ; 32(5): 511-516, 2017 10 17.
Artigo em Inglês | MEDLINE | ID: mdl-28992082

RESUMO

Lanka Mineral Sands Ltd (LMS), a government-owned company, has been mining mineral sands including monazite which contains thorium (Th) at Pulmoddai, Sri Lanka since 1957. Th emits alpha particles on decay and gamma rays are emitted by the daughter products. The cytokinesis-blocked micronucleus (MN) assay is popular for large scale radiation exposure studies as it is an easy, fast and reliable method of biodosimetry. The objective of the study was to determine the frequency of micronuclei among persons residing in the vicinity of LMS. A cross-sectional study was conducted from November 2012 to September 2016 among persons 35-45 years of age to evaluate the frequency of micronuclei in peripheral blood lymphocytes. Fifty-three employees of LMS factory, 25 residents within 5 km from LMS, 25 residents 20-25 km from LMS and 29 residents from >50 km away from LMS were included in the study. The highest median frequency of micronuclei per 1000 binucleated (BN) cells was in the group residing within 5 km from LMS with a median (IQ range) of 0.67 (0.17-2.17). The median (IQ range) of MN frequency of employees of LMS, residents 20-25 km from LMS and residents >50 km from LMS were 0.66 (0.16-1.16), 0.33 (0.00-0.67) and 0.33 (0.33-0.67), respectively. There was no significant difference in the MN frequency between employees of LMS and the group residing within 5 km from LMS. Being a resident of Pulmoddai and being exposed to X-rays were significant predictors of MN frequency. Persons residing within 5 km from LMS had a higher risk of MN formation irrespective of being employed at LMS.


Assuntos
Exposição Ambiental , Raios gama/efeitos adversos , Linfócitos/efeitos da radiação , Micronúcleos com Defeito Cromossômico/efeitos da radiação , Tório/toxicidade , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Testes para Micronúcleos , Pessoa de Meia-Idade , Dióxido de Silício , Sri Lanka/epidemiologia , Tório/química
14.
Dalton Trans ; 46(40): 13869-13877, 2017 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-28971198

RESUMO

The use of uranium and to a minor extent plutonium as fuel for nuclear energy production or as components in military applications is under increasing public pressure. Uranium is weakly radioactive in its natural isotopy but its chemical toxicity, combined with its large scale industrial utilization, makes it a source of concern in terms of health impact for workers and possibly the general population. Plutonium is an artificial element that exhibits both chemical and radiological toxicities. So far, uranium (under its form uranyl, U(vi)) or plutonium (as Pu(iv)) decorporation or protecting strategies based on molecular design have been of limited efficiency to remove the actinide once incorporated after human exposure. In all cases, after human exposure, plutonium and uranium are retained in main target organs (liver, kidneys) as well as skeleton although they exhibit differences in their biodistribution. Polymers could represent an alternative strategy as their tropism for specific target organs has been reported. We recently reported on the complexation properties of methylcarboxylated polyethyleneimine (PEI-MC) with uranyl. In this report we extend our work to methylphosphonated polyethyleneimine (PEI-MP) and to the comparison between actinide oxidation states +IV (thorium) and +VI (uranyl). As a first step, thorium (Th(iv)) was used as a chemical surrogate of plutonium because of the difficulty in handling the latter in the laboratory. For both cations, U(vi) and Th(iv), the uptake curve of PEI-MP was recorded. The functionalized PEI-MP exhibits a maximum loading capacity comprised of between 0.56 and 0.80 mg of uranium (elemental) and 0.15-0.20 mg of thorium (elemental) per milligram of PEI-MP. Complexation sites of U(vi) and Th(iv) under model conditions close to physiological pH were then characterized with a combination of Fourier transform Infra Red (FT-IR) and Extended X-Ray Absorption Fine Structure (EXAFS). Although both cations exhibit different coordination modes, similar structural parameters with phosphonate functions were obtained. For example, the coordination sites are composed of fully monodentate phosphonate functions of the polymer chains. These physical chemical data represent a necessary basic chemistry approach before envisioning further biological evaluations of PEI-MP polymers towards U(vi) and Pu/Th(iv) contamination.


Assuntos
Elementos da Série Actinoide/química , Quelantes/metabolismo , Compostos Organofosforados/química , Polietilenoimina/química , Elementos da Série Actinoide/metabolismo , Quelantes/síntese química , Quelantes/química , Humanos , Plutônio/química , Plutônio/metabolismo , Exposição à Radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Tório/química , Tório/metabolismo , Urânio/química , Urânio/metabolismo
15.
Appl Radiat Isot ; 129: 185-188, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28869870

RESUMO

The present study was to investigate the alteration of biochemical and hematological parameters on the rats exposed to natural radiation caused by britholite mineral (REE, Ca, Na)5 [(Si,P)O4]3(OH,F) within 15 days. Britholite was collected from Kuluncak mining area, Malatya, bearing radioactive 232Th isotope (average 2.68% ThO2), which is rare earth elements found high amounts. Britholite is toxic for the living animal and human and emits the radiation to natural surroundings about 0.8R/h due to its radioactive 232Th properties. In this study, animals were divided to two groups, one groups exposed to 232Th, the other group was served as control group. All animals were fed with same food and water during the experimental study (15 days). After 15 days, the hematologic and biochemical parameters (Na, K, Ca, P, Cl, Mg, glucose, cholesterol, HDL, LDL, albumin, Uric acid, AST, ALT, total protein, Fe, urea and creatine level and hormonal parameters (TSH, T3 and T4)) were analyzed The levels of serum triglyceride in the ionizing radiation group generated by 232Th isotope (p < 0.05) statistically significantly increased compared with control group value. Lymphocytes, TSH, T3 and T4 decreased in the ionizing radiation group generated by 232Th isotope while neutrophils increased in the ionizing radiation group generated by 232Th isotope. The rats exposed to ionizing radiation generated by 232Th isotope caused significant changes in the hematological and biochemical parameters and the most significantly alteration was observed in the thyroid hormonal levels, which might be due to high radiation doses within short time. These results should be kept in mind to maintain healthy life in people who lives in britholite mineral vicinity.


Assuntos
Minerais/toxicidade , Tório/toxicidade , Animais , Apatitas/química , Apatitas/toxicidade , Células Sanguíneas/efeitos da radiação , Análise Química do Sangue , Proteínas Sanguíneas/metabolismo , Relação Dose-Resposta à Radiação , Lipídeos/sangue , Masculino , Minerais/química , Ratos , Ratos Wistar , Silicatos/química , Silicatos/toxicidade , Tório/química , Hormônios Tireóideos/sangue
16.
Proc Natl Acad Sci U S A ; 114(39): 10350-10355, 2017 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-28893981

RESUMO

Hard coral cover on the Great Barrier Reef (GBR) is on a trajectory of decline. However, little is known about past coral mortality before the advent of long-term monitoring (circa 1980s). Using paleoecological analysis and high-precision uranium-thorium (U-Th) dating, we reveal an extensive loss of branching Acropora corals and changes in coral community structure in the Palm Islands region of the central GBR over the past century. In 2008, dead coral assemblages were dominated by large, branching Acropora and living coral assemblages by genera typically found in turbid inshore environments. The timing of Acropora mortality was found to be occasionally synchronous among reefs and frequently linked to discrete disturbance events, occurring in the 1920s to 1960s and again in the 1980s to 1990s. Surveys conducted in 2014 revealed low Acropora cover (<5%) across all sites, with very little evidence of change for up to 60 y at some sites. Collectively, our results suggest a loss of resilience of this formerly dominant key framework builder at a regional scale, with recovery severely lagging behind predictions. Our study implies that the management of these reefs may be predicated on a shifted baseline.


Assuntos
Antozoários/crescimento & desenvolvimento , Recifes de Corais , Monitoramento Ambiental/métodos , Aquecimento Global , Datação Radiométrica/métodos , Animais , Austrália , Tório/química , Urânio/química
17.
Artigo em Inglês | MEDLINE | ID: mdl-28737717

RESUMO

In this study, graphene Th(IV) phosphate was prepared by sol-gel precipitation method. The ion-exchange behavior of this cation-exchanger was studied by investigating properties like ion-exchange capacity for various metal ions, the effect of eluent concentration, elution behavior, and thermal effect on ion-exchange capacity (IEC). Several physicochemical properties as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) study, thermal studies, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies were also carried out. The material possessed an IEC of 1.56 meq·dry·g-1 of the exchanger and was found to be nano-composite. The selectivity studies showed that the material is selective towards Pb(II) ions. The selectivity of this cation-exchanger was demonstrated in the binary separation of Pb(II) ions from mixture with other metal ions. The recovery was found to be both quantitative and reproducible.


Assuntos
Chumbo/química , Nanocompostos/química , Fosfatos/química , Tório/química , Adsorção , Grafite/química , Troca Iônica , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
18.
Nucl Med Biol ; 51: 1-9, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28486098

RESUMO

INTRODUCTION: Alpha-emitting radionuclides have gained considerable attention as payloads for cancer targeting molecules due to their high cytotoxicity. One attractive radionuclide for this purpose is 212Pb, which by itself is a ß-emitter, but acts as an in vivo generator for its short-lived α-emitting daughters. The standard method of preparing 212Pb-labeled antibodies requires handling and evaporation of strong acids containing high radioactivity levels by the end user. An operationally easier and more rapid process could be useful since the 10.6h half-life of 212Pb puts time constraints on the preparation protocol. In this study, an in situ procedure for antibody labeling with 212Pb, using a solution of the generator nuclide 224Ra, is proposed as an alternative protocol for preparing 212Pb-radioimmunoconjugates. METHODS: Radium-224, the generator radionuclide of 212Pb, was extracted from its parent nuclide, 228Th. Lead-212-labeling of the TCMC-chelator conjugated monoclonal antibody trastuzumab was carried out in a solution containing 224Ra in equilibrium with progeny. Subsequently, the efficiency of separating the 212Pb-radioimmunoconjugate from 224Ra and other unconjugated daughter nuclides in the solution using either centrifugal separation or a PD-10 desalting size exclusion column was evaluated and compared. RESULTS: Radiolabeling with 212Pb in 224Ra-solutions was more than 90% efficient after only 30min reaction time at TCMC-trastuzumab concentrations from 0.15mg/mL and higher. Separation of 212Pb-labeled trastuzumab from 224Ra using a PD-10 column was clearly superior to centrifugal separation. This method allowed recovery of approximately 75% of the 212Pb-antibody-conjugate in the eluate, and the remaining amount of 224Ra was only 0.9±0.8% (n=7). CONCLUSIONS: The current work demonstrates a novel method of producing 212Pb-based radioimmunoconjugates from a 224Ra-solution, which may be simpler and less time-consuming for the end user compared with the method established for use in clinical trials of 212Pb-TCMC-trastuzumab.


Assuntos
Radioisótopos de Chumbo/química , Radioquímica/métodos , Rádio (Elemento)/química , Tório/química , Trastuzumab/química , Partículas alfa , Quelantes/química , Humanos , Imunoconjugados/química , Marcação por Isótopo , Doses de Radiação
19.
J Chromatogr A ; 1504: 35-45, 2017 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-28511933

RESUMO

Combining the merits of soft-templating and perchlorate oxidation methods, the first-case investigation of niobium alkylphosphonates has uncovered their unique morphology, backbone composition, thermal behavior and huge potentiality as radioanalytical separation materials. These hierarchically porous solids are random aggregates of densely stacked nanolayers perforated with worm-like holes or vesicular voids, manifesting the massif-, tower-like "polymer brush" elevated up to ∼150nm driven by the minimal surface free energy principle. These coordination polymers consist of distorted niobium (V) ions strongly linked with tetrahedral alkylphosphonate building units, exposing uncoordinated phosphonate moieties and defective metal sites. Despite the amorphous features, they demonstrate multimodal porosity covering continuous micropores, segregated mesopores and fractional macropores, beneficial for the sequestration by active Lewis acid-base center. Evidenced by the maximum distribution coefficients of thorium, lanthanides reaching 9.0×104, 9.5×104mLg-1 and large separation factor at pH≤1 20-element cocktail, this category of niobium alkylphosphonates are capable of harvesting thorium, lanthanides directly from the radionuclide surrogate, comparable to or even surpass the performance of the metal (IV) arylphosphonates counterparts. They also display appreciable SFEu/Sm ∼20 in 1molL-1 HNO3, shedding light on dual approaches to achieve the isolation of americium from curium. A combinatorial radioanalytical separation protocol has been proposed to enrich thorium and europium, revealing facile utilization of these highly stable, phosphonated hybrids in sustainable development of radioanalytical separation.


Assuntos
Nióbio/química , Polímeros/química , Tório/isolamento & purificação , Elementos da Série dos Lantanídeos/química , Elementos da Série dos Lantanídeos/isolamento & purificação , Ácidos de Lewis/química , Organofosfonatos/química , Porosidade , Tório/química
20.
Drug Dev Ind Pharm ; 43(9): 1440-1449, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28402142

RESUMO

Tumor targeting pharmaceuticals will play a crucial role in future pharma pipelines. The targeted thorium conjugate (TTC) therapeutic platform could provide real benefit to patients, whereby targeting moieties like monoclonal antibodies are radiolabelled with the alpha-emitting radionuclide thorium-227 (227Th, t1/2 = 18.7 days). A potential problem could be the accumulation of the long-lived daughter nuclide radium-223 (223Ra, t1/2 = 11.4 days) in the drug product during manufacturing and distribution. Therefore, the level of 223Ra must be standardized before administration to the patient. The focus in this study has been the removal of 223Ra, as the other progenies will have a very limited stay in the formulation. In this study, the purification of TTCs labeled with decayed 227Th has been explored. Columns packed with a strong cation exchange resin have been used to sequester 223Ra. The separation of TTC from 223Ra has been evaluated as influenced by both formulation and process parameters with a design of experiments (DOE) study; including citrate or acetate buffer, pH, buffer concentration, presence or absence of pABA + EDTA, resin amount and sodium chloride concentration. The aim was to achieve a separation with high sorption of 223Ra and accompanying low TTC sorption. The results were analyzed by multivariate analysis. Four regression models of TTC and 223Ra sorption from citrate and acetate buffered formulations were developed. The predictive accuracy of sorption in the four statistical models was given by standard deviations and confidence intervals. The TTC sorption in citrate and acetate buffered formulations was affected by the identical variables and the variation in TTC sorption was comparable for the two models. However, the DOE variables had a significantly stronger impact on the 223Ra sorption in citrate buffered formulations than the 223Ra sorption in acetate buffer. An optimal separation with a TTC sorption below 25% and 223Ra sorption above 90% can be achieved in both citrate and acetate buffered formulations. Stability studies of radiochemical purity (RCP) indicated that the measured 227Th values may be partly due to free 227Th and not TTC, but the results indicate that TTC stability may be controlled by optimizing formulation parameters. Hence, the sorption data and the regression models presented must be reviewed and further explored with regard to what is known about the stability of the TTC in the different buffered formulations.


Assuntos
Anticorpos Monoclonais/química , Cátions/química , Rádio (Elemento)/química , Anticorpos Monoclonais/metabolismo , Tampões (Química) , Química Farmacêutica , Compostos Radiofarmacêuticos , Tório/química
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