Mixture Of Th Research Articles

Selective Liquid-Liquid Extraction of Thorium(IV) from Rare-Earth Element Mixtures.

One of the major challenges in processing rare-earth element (REE) materials arises from the large amounts of radioactive thorium (Th) that are often found within REE minerals, encouraging enhanced metal separation procedures. We report here a study aimed at developing improved systems for REE processing with the goal of efficient extraction of Th(IV) from acidic solution. A tripodal ligand, TRPN-CMPO-Ph, was prepared that utilizes carbamoylmethylphosphine oxide (CMPO) chelators tethered to a tris(3-aminopropyl)amine (TRPN) capping scaffold. The ligand and its metal complexes were characterized by using elemental analysis, NMR, Fourier transform infrared spectroscopy, mass spectrometry, and luminescence spectroscopy. Using a liquid-liquid metal extraction protocol, TRPN-CMPO-Ph selectively extracts Th(IV) at an efficiency of 79% from a mixture of Th(IV), UO22+, and all rare-earth metal cations (except promethium) dissolved in nitric acid into an organic solvent. Th(IV) extraction selectivity is maintained upon extraction from a mixture that approximates a typical monazite leach solution containing several relevant lanthanide ions, including two ions at higher concentration relative to Th(IV). Comparative studies with a tris(2-aminoethyl)amine (TREN)-capped derivative are presented and support the need for a larger TRPN capping scaffold in achieving Th(IV) extraction selectivity.

Combined treatment of Taraxaci Herba and R7050 alleviates the symptoms of herpes simplex virus-induced Behçet's disease in rats

BackgroundBehçet's disease (BD) is a chronic inflammatory systemic disease that affects multiple organs. The causes of BD are still unknown, but it is primarily characterized by autoimmune reaction in the blood vessels. Current research focuses on treatments that can reduce the non-typical inflammatory responses of BD. Nevertheless, studies on improving the inflammatory effect of BD using inflammation mechanisms are still insufficient. Therefore, we conducted the integrated treatments related to inflammation modulation and achieved alleviation of symptoms in BD mice. MethodsTo understand the complex etiology of BD and compare its management, the herpes simplex virus (HSV)-induced BD mouse model was used. In order to alleviate the inflammatory response in BD mice, Taraxaci Herba (TH, herbal medicine), R7050-a TNFα inhibitor, and a mixture of TH and R7050 were injected for 2 weeks repetitively. The SCORAD index was examined to evaluate the cutaneous inflammations. In addition, histological changes and inflammatory factors were analyzed. ResultsRepetitive injection of TH and/or R7050 reduced the symptoms of BD and significantly decreased IL-6, IL-1β, and TNFα in blood sera. Moreover, this treatment reduced the ulcers and the deterioration of skin. ConclusionsThe results of our study showed that the down-regulation of inflammatory factors is related to the control of immune responses in BD models, suggesting that a mixed drug treatment may be more effective in improving the condition of BD.

ASSESSMENT OF FAST-SPECTRUM BLANKET LATTICES FOR BREEDING FISSILE FUEL FROM THORIUM AND DEPLETED URANIUM IN AN EXTERNALLY DRIVEN SUB-CRITICAL GAS-COOLED PRESSURE TUBE REACTOR

To ensure long-term nuclear energy security, it is advantageous to consider the use of externally driven sub-critical systems for producing fissile fuel to supply fleets of thermal-spectrum reactors as an alternative to using fast-spectrum or thermal-spectrum breeder reactors. Computational/analytical neutronics and heat transfer studies have been carried out for gas-cooled fuel bundle lattices with mixtures of fertile thorium and depleted uranium (DU) that could be used in the blanket region of a sub-critical fast reactor driven either by a fusion reactor in a hybrid fusion-fission reactor (HFFR) system, or an accelerator-based spallation neutron source in an accelerator driven system (ADS). The HFFR or ADS concept envisioned is one with a simple cylindrical geometry. The annular-cylindrical blanket is approximately 10 m long, can be made 2–5 m thick (1.0 m ≤ Rblanket ≤ 3.0 m to 6.0 m), and is filled with a repeating square lattice of pressure tubes filled with 0.5 m long fuel bundles that are made of (DU,Th)O2, with various mixtures of Th and DU, and refuelled periodically online. Although using blankets made of pure DUO2 or ThO2 are viable options to analyze, mixing DUO2 with ThO2 can help alleviate any potential proliferation concerns, since any 233U produced from breeding will be denatured by the presence of 238U in (DU, Th)O2. Lattice calculations demonstrate that the total fissile content in the fuel after an extended period of burnup (50 MWd/kg) will be approximately the same, regardless of the mixture of DU and thorium used, and that the content of americium and 232U in the irradiated fuel will be <0.01 wt%/initial heavy metal.

ChemInform Abstract: Two‐Dimensional Inorganic Cationic Network of Thorium Iodate Chloride with Unique Halogen—Halogen Bonds.

AbstractThe new compound [Th3O2(IO3)5(OH)2]Cl is hydrothermally synthesized from an aqueous mixture of Th(NO3)4, HIO3, and KCl (autoclave, 230 °C, 3 d).

Rapid and non-destructive determination of uranium and thorium by gamma spectrometry and a comparison with ICP-AES

A rapid, simple and non-destructive method was developed for the determination of thorium, uranium by gamma ray spectrometry (high purity Ge detector) in thorium–uranium mixture. Using the calibration curves, thorium and uranium were analyzed in synthetic samples with RSD ~2 %. Inter element effect suggested that 583 and 185.7 keV gamma lines are more suitable for the determination of Th and U, respectively in a mixture of Th–U. The newly developed method was validated by routinely employed method using synthetic samples. An ICP-AES based method was developed for the determination of uranium and thorium for comparison purpose.

High-Utilization Lattices for Thorium-Based Fuels in Heavy Water Reactors

New fuel bundle and lattice concepts to implement thorium-based fuel cycles in pressure tube heavy water reactors (PT-HWRs) have been explored to achieve maximum resource utilization. As an existing, operational technology, PT-HWRs are highly advantageous for implementing the use of thorium-based fuel cycles because of their high neutron economy and online refueling capability. A PT-HWR is flexible in that it can use one, two, or more different types of fuels in either homogeneous or heterogeneous cores to optimize power production, fuel burnup, and new fissile fuel production. In a heterogeneous PT-HWR core, higher fissile content seed fuel will be optimized for power and excess neutron production, and lower fissile content blanket fuel will be optimized for production of 233U. Five different lattice concepts were investigated for potential use in a once-through thorium cycle in a PT-HWR. The lattices involved 43-, 35-, and 21-element bundles with a central cluster of ThO2 pins, or a Zircaloy-4 (Zr-4) central displacer tube containing either stagnant D2O coolant or solid ZrO2, to help reduce coolant void reactivity (CVR). The fuel in the outer pins is a homogeneous mixture of Th and low-enriched uranium (LEU) (~5 wt% 235U/U) or reactor-grade Pu (~67 wt% fissile). The content of the LEU or Pu was varied to achieve different levels of burnup, and it is presumed that low-reactivity fuel would be used as blanket bundles. It was found that the various lattice concepts could achieve burnups ranging from ~10 to 80 MWd/kg and that the fissile utilization could be up to 60% to 100% higher than what is currently achieved in a PT-HWR using natural uranium fuel. Burnup-averaged CVR ranges from approximately +1 to +16 mk (1 mk = 100 pcm = 0.001Δk/k), depending on lattice type and fuel composition. Assuming a maximum linear element rating of ~50 kW/m, the maximum permissible bundle power ranges from ~520 to 800 kW.

Evaluation of electrospray ionisation mass spectrometry as a technique for the investigation of competitive interactions: A case study of the ternary Th‐Mn‐EDTA system

Electrospray ionisation mass spectrometry (ESI-MS) is a useful tool for exploring the speciation of solution-phase metal complexes; however, the quantification of ternary systems is challenging due to the differences in the electrospray response of different species. Here, the Th-Mn-EDTA system was investigated to evaluate the capability of ESI-MS for quantifying the species present. Increasingly complex mixtures of Th(IV), Mn(II) and EDTA were analysed using manual flow injection of samples into an HPLC grade water mobile phase delivered to an ion trap mass spectrometer fitted with an ESI interface (ThermoQuest Finnigan Mat LCQ). Mass spectra were obtained in the positive and negative ion modes over a mass-to-charge (m/z) range from 50-2000. The instrumental response to EDTA was affected by the addition of Th(NO(3))(4) but not MnCl(2), while the response to both Th-EDTA and Mn-EDTA species was affected by addition of the other metal salt. Internal standards were also found to suppress signals to different extents. Therefore, each signal suppression was carefully quantified as the solution became more complex, and signal correction factors were used in conjunction with regular external calibration. Mixed metal signals were quantified adequately. This study showed the complexity of quantifying a ternary system involving different co-existing species. Nonetheless, the step-wise protocol developed provided quantitative data on the displacement of Mn from its EDTA complex by Th.

Fabrication of functional poly(thiophene) electrode for biosensors

Three-type polymer electrodes such as poly(Th), poly(Th–AP) and poly(Th–AP–TAA) were fabricated, respectively, by electro-oxidative polymerization of thiophene (Th), mixture of Th and 2-aminophenol (AP), and mixture of Th, AP and 3-thiopheneacetic acid (TAA) on the surface of indium tin oxide (ITO) glass by cyclic voltammetry (CV). The polymer electrodes were electrodeposited by cycling the potential between −1.0 and +2.5 V in acetonitrile containing 50 mM tetrabutylammoniumhexafluorophosphate (TBAF 6P). The surface morphology of polymer electrodes was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis. The surface morphology of the poly(Th) showed typical roughness and fractal-like growth patterns, and the morphologies of poly(Th–AP) and poly(Th–AP–TAA) were dramatically changed. The water contact angle at the poly(Th–AP–TAA) (23°) is lower in comparison to poly(Th) (47°). The functional groups (–OH) and carboxylic acid (–COOH) group play an important role. Horseradish peroxidase was loaded onto poly(Th–AP–TAA) surface and used to test the sensing of H 2O 2.

Appraisal of the chemical modification process for the determination of lead by ultrasonic slurry sampling-electrothermal atomic absorption spectrometry

Conventional and permanent modifiers separately and joined together were investigated for the determination of lead in coal fly ash samples by ultrasonic slurry sampling-electrothermal atomic absorption spectrometry (SS-ETAAS). Thorium in solution alone and combined with rhodium as a permanent modifier provided the most consistent performance in terms of precision and accuracy. Evidence about the action mechanism of the chemical modifiers was derived by scanning electron microscopy (SEM)-energy dispersive (ED) X-ray spectrometry from the solid residue on the graphite platforms that had previously been submitted to several temperatures. Mixtures of Th–Pb and Rh–Pb oxides were stated to be the most plausible precursor species of the lead gas phase atoms for Th-based modifiers. By contrast, oxygen-free Rh–Pb metallic species were found using the permanent modifier alone. The effects of the modifiers, the matrix components and the slurry parameters, as well as the pyrolysis and atomization temperatures, on the Pb atomic absorption signals were also studied. Calibration was carried out against aqueous standard solutions. The reliability of the whole procedure was validated by analyzing various coal fly ash certified reference materials. The between-batch precision (n = 7) was better than 4.5% for lead concentrations of 50 μg l−1. The detection limits and characteristic masses were 0.17 μg l−1 and 18 pg with thorium added in solution and 0.25 μg l−1 and 27 pg with rhodium, as permanent modifier, combined with thorium in solution for a 10 μl volume injected.

CD8+ T Cell Immunity Against a Tumor/Self-Antigen Is Augmented by CD4+ T Helper Cells and Hindered by Naturally Occurring T Regulatory Cells

CD4(+) T cells control the effector function, memory, and maintenance of CD8(+) T cells. Paradoxically, we found that absence of CD4(+) T cells enhanced adoptive immunotherapy of cancer when using CD8(+) T cells directed against a persisting tumor/self-Ag. However, adoptive transfer of CD4(+)CD25(-) Th cells (Th cells) with tumor/self-reactive CD8(+) T cells and vaccination into CD4(+) T cell-deficient hosts induced autoimmunity and regression of established melanoma. Transfer of CD4(+) T cells that contained a mixture of Th and CD4(+)CD25(+) T regulatory cells (T(reg) cells) or T(reg) cells alone prevented effective adoptive immunotherapy. Maintenance of CD8(+) T cell numbers and function was dependent on Th cells that were capable of IL-2 production because therapy failed when Th cells were derived from IL-2(-/-) mice. These findings reveal that Th cells can help break tolerance to a persisting self-Ag and treat established tumors through an IL-2-dependent mechanism, but requires simultaneous absence of naturally occurring T(reg) cells to be effective.

FACILITATED TRANSPORT OF Th(IV) ACROSS BULK LIQUID MEMBRANE BY DI(2-ETHYLHEXYL)PHOSPHORIC ACID

Di(2-ethylhexyl) phosphoric acid (DEHPA) has been successfully used as a carrier for the selective and efficient transport of Th(IV) across a bulk liquid membrane (BLM) of chloroform. The feed comprised of a solution of pure Th(IV) or a binary mixture of Th(IV) and a cation, such as Na+, K+, Ca2+, Mg2+, Cu2+, Pb2+, La3+, Fe3+, or UO2+ 2, in water maintained at pH 2, while 0.1 mol/L hydrochloric acid served as a stripping agent in the receiving compartment of the permeation cell. Greater than 99% of Th4+ selectively permeated across the membrane in less than 3 h, while the transport of other cations present along with thorium was less than 3% during the same time. Selectivity of the transport of thorium was greatly affected by the presence of Fe3+ and UO2+ 2 in the feed solution. Fe3+ could be effectively masked by the addition of SCN− or citric acid to the feed solution but the cotransport of UO2+ 2 could only be partially reduced by the addition of carbonate or thiocyanate to the feed solution.

Effects of Surfactant PDFO on Photoluminescence of Porous Silicon

On the performance of the hydrogen peroxide method for Th-determination we encountered some difficulties, namely the formation of the insoluble matter occured in the nearly neutral solution after evaporation. We carried out the Th-determination in the mixture of the Th and some kind of the rare earth, and found that the insoluble matter was not formed in case of the mixture of Th and some kind of rare earth, but formed in case of Monazite. The formation of the insoluble matter in the case of Monazite sand, however, could be avoid by using the beaker instead of the evaporating dish and by adding the water repeatedly before it was completely evaporated to dryness.

Induction of a cytotoxic T cell response by co-injection of a T helper peptide and a cytotoxic T lymphocyte peptide in incomplete Freund's adjuvant (IFA): further enhancement by pre-injection of IFA alone.

We have previously demonstrated that it is possible to induce a consistent and strong cytolytic T lymphocyte (CTL) response to synthetic peptides, corresponding to poorly immunogenic malaria CTL epitopes, by co-injecting them with peptides representing defined T helper (Th) epitopes in incomplete Freund's adjuvant (IFA). In this study we have tested different immunization protocols to improve further the elicitation of the CTL response. We show that the CTL response to a mixture of Th + CTL peptides administered in IFA was further enhanced by a previous injection of the Th epitope peptide in IFA. Moreover, we found that the response could be significantly augmented by a pre-injection of IFA alone. This enhancement was observed only if the Th epitope was also present in the second injection. The number of lymph node cells recovered was 2-3-fold higher in mice pre-injected with IFA, but the increase in specific CTL activity, expressed as lytic units per animal, by pre-injection of IFA was at least 10-20-fold. Thus, pre-injection of IFA clearly increases the magnitude of a subsequent CTL response.

Immunohistologic Pattern of the Portal T-Lymphocyte Infiltration in Hepatic Allograft Rejection

Monoclonal antibodies were used to identify helper T cells (TH) and suppressor/cytotoxic T cells (TS/C) in liver allograft biopsy specimens obtained 7,21,90,180, and 365 days postoperatively and then annually or during episodes of graft dysfunction and after treatment of rejection episodes. Biopsy specimens were obtained from 70 hepatic allografts from patients treated with cyclosporine and corticosteroids. Rejection was diagnosed by the presence of appropriate laboratory and light microscopic findings and at least 16 weeks of follow-up to exclude other causes of graft dysfunction. Three immunohistologic patterns were noted: no or only a trace of T lymphocytes, predominantly TH infiltrate with or without a small amount of TS/C cells (portal TH), and a mixture of TH with an equal or greater number of TS/C infiltrate (portal mix). Of 68 biopsy specimens obtained during quiescent periods, only 3 had a portal tract T-lymphocyte infiltrate. Of 30 protocol biopsy specimens, 24 contained such an infiltrate a mean of 12.4 days before biochemical and routine histologic indications of rejection in the allograft. At the time of the rejection episode, 33 biopsy specimens were immunohistologically labeled; portal tract T-lymphocyte infiltrate was predominantly TH in 8 and a mixture of TH and TS/C in 25. All rejection episodes with a predominantly TH pattern responded to methylprednisolone. Of the 25 rejection episodes with a portal mix pattern, only 3 responded to methylprednisolone. Eighty-seven biopsy specimens were obtained more than 10 days after treatment of rejection.(ABSTRACT TRUNCATED AT 250 WORDS)

On-line determination of actinides by energy-dispersive XRF induced by γ-emitting radionuclides

One of the most suitable methods for analytical on-line determination of actinides in solutions of reprocessing plants is X-ray fluorescence analysis. For stability and for economy of space radionuclides are preferable as excitation sources. The excitation and the measurement of the K-lines has a number of advantages in comparison to the L-lines: the fluorescence yield is higher, the penetration is better, and the resolution is better. To lower the background due to scattering radionuclides with γ-energies of about 300 keV are preferable.75Se,113Sn,125Sb,131I,133Ba,192Ir,203Hg, and231Pa have been proposed,133Ba was used in this work. The following arrangement was built up: a HPGe-detector, two133Ba sources in 45o position, detector and source collimators made from tin and a sample tube diameter of 130 mm with technical glass or stainless steel of up to 6 mm thickness as tubing material. The measuring time was 10 min. Using this arrangement the calibration curve for uranium was measured in the range from 5 mg/l to 400 g/l. In mixtures of Th and U interferences were observed and corrected for. Samples of Np and Pu were also measured. Determination of Th, U, Np and Pu in mixtures in absence and in presence of other radionuclides is discussed.

Immunohistologic labeling as an indicator of liver allograft rejection.

Monoclonal antibodies were used to identify T-helper cells (TH) and T-suppressor/cytotoxic cells (TS/C) in biopsy specimens obtained 7, 21, 90, 180, and 365 days postoperatively, and during episodes of graft dysfunction, from 34 consecutive liver transplant patients treated with cyclosporine and steroids. Rejection was diagnosed by the presence of appropriate laboratory and light microscopic findings and at least 8 weeks of follow-up to exclude other causes of graft dysfunction. Four immunohistologic patterns were seen--no labeled cells (No), only lobular TS/C, only portal TH, and a portal mixture of TH and TS/C (mix). Of 36 specimens with the No or only lobular TS/C pattern, 29 were not associated with rejection. Of the 39 specimens with the portal TH or portal Mix pattern, 33 were associated with a rejection episode. In addition, in nine specimens from patients with no biochemical or routine histologic evidence of rejection, the presence of portal TH or a portal mix indicated immunologic rejection 5 days to 5 weeks before biochemical and routine histologic evidence of it was manifested. Immunohistologic labeling appears to be an early indicator of liver allograft rejection.

A real-time tritium monitor with an MPC proportional response to airborne mixtures of TH and THO

A fast response tritium-in-air monitor that can detect airborne HT and HTO in proportion to the occupational maximum permissible concentration (MPC) of either species has been developed at Lawrence Livermore Laboratory. The sample gas is selectively filtered through a dimethyl silicon membrane resulting in a throughput that is 400 times greater for HTO than for HT. After filtering, the tritium is detected in a 10 cm 3 flow-through proportional counter. A short accumulation time, for a 5 s response to high levels of tritium (⩾ 1000 MPC), and a longer accumulation time, for a 60 s response to low levels of tritium (⩾ 10 MPC), are included. To avoid false alarms, the short accumulation counter is continuously compared to a pulser set at three standard deviations above background.