Raman and X‐ray Studies of Uranium–Lanthanum‐Mixed Oxides Before and After Air Oxidation

UO₂ samples doped with 6, 11, 22 mol% lanthanum were examined before and after air oxidation. To verify the formation of uranium–lanthanum‐mixed oxide solid solutions, powder X‐ray diffraction (XRD) analyses of the crystalline phases in the materials were carried out. The presence of oxygen vacancies in the La‐doped UO₂ samples was identified by Raman spectrometry. It was evidenced by changes induced in the Raman spectra by air oxidation. This latter was carried out either by increasing the Raman laser power or by thermally treating the samples at 500 K for 370 h. In addition, oxidation behavior differences of pure and La‐doped UO₂ samples were reported by comparing XRD and Raman results of the samples before and after air oxidation. It was shown that the concentration of the M₄O₉ (M: U, La) phase increased with increasing content of La, whereas inhibition for the formation of M₃O₈ phase was observed.     

Acute Intake of Plant Stanol Esters Induces Changes in Lipid and Lipoprotein Metabolism‐Related Gene Expression in the Liver and Intestines of Mice

The kinetics of plant stanol uptake and routing in 8‐week‐old C57BL/6J mice were determined after a plant stanol ester gavage. In addition, acute changes in intestinal and hepatic gene expression were investigated. Mice were fed a plant sterol/stanol poor diet from weaning. At the age of 8 weeks, they received an oral gavage consisting of 0.25 mg cholesterol + 50 mg plant stanol esters dissolved in olive oil. Animals were euthanized at different time points. In a second comparable set‐up, mesenteric lymph‐cannulated versus sham‐operated mice received the same oral gavage, which was now deuterium labeled. Intestinal and hepatic sitostanol concentrations increased within 15 min post‐gavage. This rapid hepatic appearance was absent in lymph‐cannulated mice, suggesting a very fast lymph‐mediated uptake. Hepatic mRNA expression of SREBP2 and its target genes rapidly decreased, whereas expression of LXR target genes increased. The intestinal SREBP2 pathway was increased, whereas the expression of LXR target genes hardly changed. The fivefold and sixfold increased expression of intestinal LDLr and PCSK9 is suggestive of TICE activation. We conclude that in C57BL/6J mice plant stanol kinetics are fast, and affect intestinal and hepatic gene expression within 15 min postprandial after lymph‐mediated uptake.     

Monitoring of mercury,arsenic, and lead in traditional Asian herbal preparations on the Dutch market and estimation of associated risks

Traditional herbal preparations used in Ayurveda, traditional Chinese medicine, traditional Tibetan medicine, and other Asian traditional medicine systems may contain significant amounts of mercury, arsenic or lead. Though deliberately incorporated in Asian traditional herbal preparations for therapeutic purposes, these constituents have caused intoxications worldwide. The aim of this study was therefore to determine mercury, arsenic, and lead levels in Asian traditional herbal preparations on the Dutch market. A total of 292 traditional herbal preparations used in Ayurveda, traditional Chinese medicine, and traditional Tibetan medicine were sampled between 2004 and 2007. Samples were mostly multi-ingredient traditional herbal preparations containing herbs and minerals. The labeling of less than 20% of the traditional herbal preparations suggested the presence of mercury, arsenic or lead. These elements were shown by inductively coupled mass spectrometry (ICP-MS) in 186 (64%) of 292 traditional herbal preparations. Estimated weekly mercury, arsenic, and lead intake levels were calculated for each traditional herbal preparation from the analytically determined concentrations and the recommended dose. A total of 59 traditional herbal preparations (20%) were likely to result in intakes of these elements significantly exceeding safety limits. Of these 59 traditional herbal preparations, intake estimates for 50 traditional herbal preparations significantly exceeded the safety limit for mercury (range = 1.4–1747 mg week^?1); intake estimates for 26 traditional herbal preparations significantly exceeded the safety limit for arsenic (range = 0.53–427 mg week^?1) and intake estimates for eight traditional herbal preparations were significantly above the safety limit for lead (range = 2.6–192 mg week^?1). It is concluded that the mercury, arsenic, and lead contents of traditional herbal preparations used in Ayurveda, traditional Chinese medicine, and traditional Tibetan medicine remain a cause for concern and require strict control.     

Fabrication of zirconia-based targets for transmutation

The fabrication of homogeneous (Am,Y,Zr)O_2−x pellets and heterogeneous pellets, containing (Am,Y,Zr)O_2−x spheres dispersed in an inert matrix, by dust-free processes has been investigated. Due to the high activity of americium, the preparatory fabrication tests and process development are being carried out using cerium analogue element. The sol gel route is used to produce highly porous Y_0.15Zr_0.85O_2−x spheres, which are then infiltrated with a cerium nitrate solution to give (Ce,Y,Zr)O_2−x. The goal (28 wt% Ce) can be achieved. Homogeneous targets with densities up to 94 %TD have been obtained.     

Slow fusion of liposomes composed of membrane-spanning lipids

Vascular calcification (VC), which is described in the elderly and in diabetics, is frequently seen in uraemia. It is usually regarded as having little significance. We studied the roentgenological appearance of VC in a homogeneous group of 38 long-hours haemodialysis patients whose longevity on dialysis allowed sustained (10-25 years) follow-up, including annual skeletal surveys and thrice-yearly clinical examinations and biochemical profiles. We compiled a dossier of clinical and laboratory parameters from the start of dialysis to the present day. We were able to analyze the natural history of VC and to determine which clinical parameters were linked with progression. We found that VC became steadily more prevalent-at dialysis onset present in 39% of the patients, but in 92% after an average dialysis duration of 16 years, with a mean onset 9.7 years after starting dialysis. As well as becoming more prevalent, the calcification became progressively more severe in most patients. There were two patterns of VC: axial (aorta and iliac and femoral arteries), seen alone in 32% of the patients, and peripheral (digital arteries), seen alone in 3% of patients. Most patients (65%) had evidence of both types. Calcification was scored for site and severity. Patient age (r = 0.57, p < 0.001), systolic blood pressure (r = 0.54, p < 0.001), hyperparathyroidism (reduced progression after parathyroidectomy), plasma phosphate (r = 0.34, p = 0.042), and vitamin D concentrations (r = 0.53, p < 0.001) were the principal determinants of severity and rate of progression of VC in this population. There was a weak negative association between progression and serum ferritin (r = -0.33, p = 0.046). The reduced vessel compliance that results from VC is likely to be cardiovascularly deleterious. In severe cases, tissue perfusion or vascular access for haemodialysis can be compromised. VC and accelerated cardiovascular mortality are common to uraemia, diabetes, and systolic hypertension in the elderly. Better understanding of these pathological processes may permit intervention and possibly lead to a reduction in cardiovascular mortality.     

Amplified expression, purification and functional reconstitution of the dipeptide and tripeptide transport protein of Lactococcus lactis

Transport of hydrophilic dipeptides and tripeptides into Lactococcus lactis is mediated by a proton-motive-force-driven peptide-transport protein (DtpT) that shares similarity to eukaryotic peptide transporters, e.g. from yeasts, plants, and the kidney and small intestine of rabbit, man and rat. The expression level of DtpT protein in L. lactis was increased (20-40-fold) to approximately 10% of total integral membrane protein by means of a low-copy-number vector and selecting the appropriate growth conditions. Membrane vesicles bearing the DtpT-His6 protein (containing a C-terminal factor-Xa cleavage site and a six-histidine-tag) showed a Pro-Ala uptake activity that was half that of membranes containing the wild-type protein. The activity in the DtpT-His6 membrane vesicles increased at least 50% upon removal of the His6 tag from the protein. More than 95% DtpT was solubilized from L. lactis membranes in the presence of 1% (mass/vol.) n-dodecyl-beta-D-maltoside, and approximately 2 mg DtpT-His6 was purified by Ni2+-chelate affinity chromatography from 100 mg membrane protein. Purified DtpT-His6 was reconstituted unidirectionally into detergent-saturated formed liposomes, which were prepared from Escherichia coli phospholipid and egg phosphatidylcholine; the detergent was removed by adsorption to polystyrene beads. The highest uptake activities were obtained when DtpT was incorporated into liposomes that were treated with a low amount of n-dodecyl-beta-D-maltoside (onset of liposome solubilization). The uptake activity could be improved by addition of NaCl (200 mM) and lipids (2 mg/ml) during the solubilization, purification and reconstitution steps.     

Thermodynamic modelling of LiF-LnF3 and LiF-AnF3 phase diagrams

The phase diagrams of the LiF-LnF₃ series, where Ln = La-Sm, and of LiF-AnF₃, where An = U, Pu, have been optimized using Redlich-Kister functions. The phase diagrams of LiF-AmF₃ and LiF-PuF₃-AmF₃ have been calculated. The necessary Gibbs energy functions for americium trifluoride were defined by use of a semi-empirical method. The excess Gibbs energy terms, which are expressed as Redlich-Kister polynomials and describe the effect of interaction between the two fluoride components in the liquid phase, were obtained by translating the trends observed in the lanthanide trifluoride series into the actinide series. A single eutectic has been found in the LiF-AmF₃ system with the eutectic point at ?33 mole% AmF₃ and at ?951 K.     

Determination of exposure to benzene, toluene and xylenes in Turkish primary school children by analysis of breath and by environmental passive sampling

Benzene, toluene, m/p-xylene and o-xylene (BTX) are toxic volatile organic compounds and ubiquitous air pollutants. Smoking and consumer products are indoor sources of BTX, whereas traffic and industrial activities are primary sources contributing to outdoor levels of BTX. The aim of this study was to characterize exposure of children to BTX by personal air sampling using diffusive samplers and by analysis of end-exhaled air. For this study, 101 children of 10-11 years of age were recruited from four primary schools in Southern Turkey during the warm season (May 2008). Two schools were situated in a residential area near primary and secondary iron and steel works (Payas) and two schools were located in a non-industrialized city (Iskenderun). The children and their parents were visited at home for an interview and to identify possible sources of BTX in the residence. Median concentrations of benzene determined by diffusive samplers were higher in Payas (4.1 μg/m³) than in Iskenderun (2.7 μg/m³, p < 0.001). For toluene, no differences were observed, whereas for xylene isomers air concentrations tended to be lower for children living in Payas. The median end-exhaled air concentrations were 8.2, 29, 3.8, and 5.7 pmol/L for benzene, toluene, m/p-xylene and o-xylene, respectively (Payas), and 6.9, 25, 4.9, and 6.0 pmol/L, respectively (Iskenderun). Concentrations of toluene in end-exhaled air were 50% higher in children living with household members who smoked indoors (p < 0.05) and benzene in end-exhaled air was more than 3-fold higher for those children who were exposed to tobacco smoke inside a vehicle (p < 0.001). End-exhaled concentrations of benzene were also higher in children living in a residence with an attached garage (p < 0.05). These exposure modifying factors were not identified when using the results obtained with diffusive samplers.     

Melting behaviour of oxide systems for heterogeneous transmutation of actinides. III. The system Am–Mg–O

Unknown thermodynamic data of a number of americium oxides were estimated. Phase diagrams of related binary and ternary systems in the Am–Mg–O system were calculated by transposing solution model parameters of the Pu–Mg–O system to the Am–Mg–O system. According to the calculated results, the liquid phase in the MgO–AmO_2−x system starts to form at 1930 K in the oxygen pressure range 4.3×10⁻⁷ to 4.5 bar, and at the temperature varying from 2221 K to 2356 K at an oxygen pressure higher than 4.5 bar.