Electrochemistry of thorium in LiCl-KCl eutectic melts

This work presents a study of the electrochemical properties of Th chloride ions dissolved in a molten LiCl-KCl eutectic, in a temperature range of 693-823 K. Transient electrochemical techniques such as cyclic voltammetry and chronopotentiommetry have been used in order to investigate the reduction mechanism on a tungsten electrode and the diffusion coefficient of dissolved Th ions. All techniques showed that only one valence state was stable in the melt. The reduction into Th metal was found to occur according to a one-step mechanism, through an irreversible reaction controlled by a nucleation process which requires an overpotential of several 100 mV. At 723 K, the diffusion coefficient is DTh(723K) = 3.7 ± 0.2·10-5 cm2.s-1. EMF measurements indicated that, at 723 K, the standard apparent potential is *0ThCl4 /Th) E (723 K) = - 2.582 V vs. Cl2/Cl-, and the activity coefficient γThCl4(723 K) = 8·10-3 on the mole fraction scale (based on a pure liquid reference state)

Electrochemistry of uranium in molten LiF–CaF2

This article is focused on the electrochemical behaviour of U ions in molten LiF–CaF2 (79–21 wt.%) eutectic. On aWelectrode, U(III) is reduced in one step to U metal and U(III) can be also oxidised to U(IV). Both systems were studied by cyclic and square wave voltammetry. Reversibility of both systems for both techniques was verified and number of exchanged electrons was determined, as well as diffusion coefficients for U(III) and U(IV). The results are in a good agreement with previous studies. On a Ni electrode,the depolarisation effect due to intermetallic compounds formation was observed. Electrorefining of U metal in a melt containing U and Gd ions was carried out using a reactive Ni electrode with promising results

Minipig cytochrome P450 3A, 2A and 2C enzymes have similar properties to human analogs

BACKGROUND: The search for an optimal experimental model in pharmacology is recently focused on (mini)pigs as they seem not only to be an alternative source of cells and tissues for xenotherapy but also an alternative species for studies on drug metabolism in man due to similarities between (mini) pig and human drug metabolizing systems. The purpose of this work is to characterize minipig liver microsomal cytochromes P450 (CYPs) by comparing their N-terminal sequences with corresponding human orthologs. RESULTS: The microsomal CYPs exhibit similar activities to their human orthologous enzymes (CYP3A4, nifedipine oxidation; 2A6, coumarin 7-hydroxylation; 2D6, bufuralol 1'-hydroxylation; 2E1, p-nitrophenol hydroxylation; and 2C9, tolbutamide hydroxylation). Specific minipig CYP (2A, 2C and 3A) enzymes were partially purified and proteins identified by immunostaining (using antibodies against the respective human CYPs) were used for N-terminal amino acid sequencing. From comparisons, it can be concluded that the sequence of the first 20 amino acids at the N-terminus of minipig CYP2A is highly similar to human CYP2A6 (70% identity). The N-terminal sequence of CYP2C shared about 50% similarity with human 2C9. The results on the minipig liver microsomal CYP3A yielded identical data with those obtained for amino acid sequences of the pig CYP3A29 showing 60% identity with human CYP3A4. CONCLUSIONS: Thus, our results further support the view that minipigs may serve as model animals in pharmacological/toxicological studies with substrates of human CYP enzymes, namely, of the CYP3A and CYP2A forms

Investigation of electrorefining of metallic alloy fuel onto solid Al cathodes

This work concerned the electrorefining of UZr and UPuZr alloys on a solid aluminium cathode, in the LiCl-KCl eutectic melt containing U3+, Pu3+, Np3+, Zr2+ or Zr 4+, Am3+, Nd3+, Y3+, Ce3+ and Gd3+ chlorides. During constant current electrolyses, the use of a cathodic cut-off potential (-1.25 V vs. Ag/AgCl) allowed to selectively deposit actinides (mainly U), while lanthanides remainedin the salt. The aim was to determine the maximal load achievable on a single aluminium electrode. The total exchange charge was 4300 C, which represents the deposition of 3.72 g of actinides in 4.17 g Al, yielding a composition of 44.6 wt% An in Al. It was shown that the melting of the cathode contributed to increase the total amount of actinides deposited on the aluminium

Recovery of actinides from actinide-aluminium alloys by chlorination: Part I

Pyrochemical processes in molten LiCl–KCl are being developed in ITU for recovery of actinides from spent nuclear fuel. The fuel is anodically dissolved to the molten salt electrolyte and actinides are electrochemically reduced on solid aluminium cathodes forming solid actinide–aluminium alloys. A chlorination route is being investigated for recovery of actinides from the alloys. This route consists in three steps: Vacuum distillation for removal of the salt adhered on the electrode, chlorination of the actinide– aluminium alloys by chlorine gas and sublimation of the formed AlCl3. A thermochemical study showed thermodynamic feasibility of all three steps. On the basis of the conditions identified by the calculations, experiments using pure UAl3 alloy were carried out to evaluate and optimise the chlorination step. The work was focused on determination of the optimal temperature and Cl2/UAl3 molar ratio, providing complete chlorination of the alloy without formation of volatile UCl5 and UCl6. The results showed high efficient chlorination at a temperature of 150 °C

Spectroscopic Approach to Correction and Visualisation of Bright-Field Light Transmission Microscopy Biological Data

The most realistic information about the transparent sample such as a live cell can be obtained only using bright-field light microscopy. At high-intensity pulsing LED illumination, we captured a primary 12-bit-per-channel (bpc) response from an observed sample using a bright-field microscope equipped with a high-resolution (4872x3248) image sensor. In order to suppress data distortions originating from the light interactions with elements in the optical path, poor sensor reproduction (geometrical defects of the camera sensor and some peculiarities of sensor sensitivity), we propose a spectroscopic approach for the correction of this uncompressed 12-bpc data by simultaneous calibration of all parts of the experimental arrangement. Moreover, the final intensities of the corrected images are proportional to the photon fluxes detected by a camera sensor. It can be visualized in 8-bpc intensity depth after the Least Information Loss compression [Lect. Notes Bioinform. 9656, 527 (2016)].Comment: 17 pages, 11 figure

Electrorefining of U-Pu-Zr-alloy fuel onto solid Aluminium cathodes in molten LiCl-KCl

An electrorefining process in molten chloride salts using solid aluminium cathodes is being developed at ITU to recover actinides (An) from the spent nuclear fuel. The maximum possible loading of aluminium electrodes with actinides was investigated during the electrorefining of UPuZr alloy in a LiCl-KCl eutectic at 450°C. Two different electrolytic techniques were applied during the experiment and almost 6000 C has been passed, corresponding to 3.7 g of deposited actinides. A very high capacity of aluminium to retain actinides has been proven as the average Al:An mass ratio was 1:1.58 for galvanostatic and 1:2.25 for potentiostatic mode. The obtained deposits were characterized by XRD and SEM-EDX analysis and alloys composed of (U,Pu)Al3 were detected. The influence of zirconium co-oxidation during the process was also investigated and the presence of dissolved Zr ions in the melt yielded a significant deterioration of the quality of the deposit

Single-track sequencing for genotyping of multiple SNPs in the N-acetyltransferase 1 (NAT1) gene

BACKGROUND: Fast, cheap and reliable methods are needed to identify large populations, which may be at risk in relation to environmental exposure. Polymorphisms in NAT1 (N-acetyl transferase) may be suitable markers to identify individuals at risk. RESULTS: A strategy allowing to address simultaneously 24 various genetic variants in the NAT1 gene using the single sequencing reaction method on the same PCR product is described. A modified automated DNA sequencing using only one of the sequence terminators was used to genotype PCR products in single-track sequencing reactions of NAT1 and was shown to be universal for both DNA sequencing using labeled primers and labeled nucleotides. By this method we detected known SNPs at site T640G, which confers the NAT1*11 allele with frequency of 0.036, further T1088A and C1095A with frequency of 0.172 and 0.188, respectively and a deletion of TAATAATAA in the poly A signal area with a frequency 0.031. All observed frequencies were in Hardy Weinberg equilibrium and comparable to those in Caucasian population. The single-track signatures of the variant genotypes were verified on samples previously genotyped by RLFP. CONCLUSIONS: The method could be of great help to scientists in the field of molecular epidemiology of screening of large populations for known informative biomarkers of susceptibility, such as NAT1

Recovery of actinides from actinide–aluminium alloys by chlorination: Part II

A chlorination route is being investigated for recovery of actinides from actinide–aluminium alloys, which originate from pyrochemical recovery of actinides from spent metallic nuclear fuel by electrochemical methods in molten LiCl–KCl. In the present work, the most important steps of this route were experimentally tested using U–Pu–Al alloy prepared by electrodeposition of U and Pu on solid aluminium plate electrodes. The investigated processes were vacuum distillation for removal of the salt adhered on the electrode, chlorination of the alloy by chlorine gas and sublimation of the AlCl3 formed. The processes parameters were set on the base of a previous thermochemical study and an experimental work using pure UAl3 alloy. The present experimental results indicated high efficiency of salt distillation and chlorination steps, while the sublimation step should be further optimised

Nanomechanical testing of Ti/Ni multilayer thin films

The main aim of the present work was to study the dependence of mechanical properties of Ti/Ni multilayer thin films on the thicknesses of constituent Ti and Ni layers. The multilayer thin films were made by depositing Ti and Ni layers alternately on single crystalline silicon substrates using magnetron sputtering method. Thickness of individual Ti and Ni layers varied from 1.7 nm to 100 nm, the total multilayer thickness was around 1 µm. The mechanical properties were characterized by means of nanoindentation experiments using a Hysitron dual head TI950 triboindenter equipped with diamond Berkovich tip in both static and dynamic loading regime in the load range from 50 µN to 11 mN. Moreover, nanoindentation tests were performed at elevated temperatures up to 500 oC using a Hysitron xSol heating stage. The nanoindentation data were evaluated using the recently developed home-made Nanoindentation General Evaluation Tool (NIGET) [1] software for independent analysis of loading and unloading curves which includes among others a basic treatment of uncertainties and systematic errors that are missing in commercial software provided together with instrumented indentation testing devices. The NIGET software has a graphical interface which uses libraries of the open source software Gwyddion [2]. The nanoindentation results were correlated with microstructure studies using XRD (X-ray diffraction technique), a Tescan LYRA 3XMU FEG/SEM×FIB scanning electron microscope (SEM), a Philips CM12 STEM transmission electron microscope (TEM) and a JEOL JEM-2100Fhigh resolution TEM. Thin lamellar cross sections for TEM observations were prepared using a focused ion beam (FIB) in SEM from two locations in each sample: an undisturbed layer and a central region of indentation print made with Berkovich tip with a relatively high load from the range of 0.5 to 1N. Please click Additional Files below to see the full abstract