The ratio of the hydrogen and manganese neutron absorption cross sections,
Mn, is a most important parameter in the determination of radioactive neutron source strength by the manganese bath technique. The ratio is well measured by observing the change in56Mn activity induced in the manganese bath by a fixed neutron source as the manganese concentration of the bath is changed. In the present study, the neutron source was a Maxwellian beam from252Cf. Concentrations were determined by the two methods: volumetric and gravimetric. The cross section ratio has turned out to be
Authors:Y. Choi, B. S. Shin, M. G. Kim, S. W. Shin, H. W. Choo, T. H. Kim, H. C. Jang, and S. D. Yoo
Capsaicin has been reported to exhibit an inhibitory effect on the P-glycoprotein (P-gp) function in vitro. To investigate its concentration-dependent effect in vivo, a sensitive assay that can characterize the absorption and disposition of capsaicin needs to be developed. This study reports the development of a sensitive LC-MS/MS assay for the determination of capsaicin in mouse plasma. The sample pretreatment involved a one-step extraction of 20 μL plasma with t-butyl methyl ether. Separations were achieved on a C18 column and the detection was performed on an LC-ESI-MS/MS by multiple reaction monitoring. The assay was linear over a wide concentration range from 0.325 to 650 ng mL−1 (r > 0.999), with a LLOQ of 0.325 ng mL−1. The developed method was applied to i.v. (dose 0.325 and 0.65 mg kg) and oral absorption (dose 40 mg kg) studies in mice. After i.v. injection, the t1/2,λz, Vz and CLs ranged from 0.13–0.16 h, 127.6–141.8 mL, and 547.3–775.4 mL/h, respectively. After oral administration, a secondary peak was observed and the terminal half-life was prolonged (1.51 h). Capsaicin was poorly absorbed, with the absolute oral bioavailability (F) ranging from 1.02% to 1.56%. The developed assay may be useful in studies where sample volumes are limited.
Two complimentary spectroscopic techniques, X-ray absorption and fluorescence spectroscopy have been conducted at spatial
scales of 1 to 25 μm on uranium contaminated soil sediments collected from two former nuclear materials processing facilities
of the DOE: Fernald, OH and Savannah River Site, SC. A method of imbedding particles in a non-reactive Si polymer was developed
such that individual particles could be examined before and after extraction with a wide range of chemicals typically used
in sequential extraction techniques and others proposed forex situ chemical intervention technologies. Using both the micro-X-ray fluorescence (XRF) and micro-X-ray Absorption Near Edge Structure
(XANES) techniques, both elemental and oxidation state distribution maps were generated on individual particles before and
following chemical extraction. XANES can determine the relative proportion of U(VI) and U(IV) in phases comprising individual
particles before and after extraction and showed that greater than 85% of the uranium existed as hexavalent U(VI). Fluorescence
spectra of contaminated particles containing mainly U(VI) revealed populations of uranyl hydroxide phases and demonstrated
the relative efficacy and specificity of each extraction method. Correlation of XAS and fluorescence data at micron scales
provides information of U oxidation state as well as chemical form in heterogeneous samples.
Authors:K. Nomura, S. Kobayashi, K. Hashimoto, Ts. Sawada, Z. Homonnay, and A. Vértes
The CO2 absorption properties and the microstructure of (Ba,Ca)(Fe,Mg)O3- have been studied by TGA, XRD, and Mössbauer spectrometry. Paramagnetic doublets of FeIV and FeIII appeared in the Mössbauer spectra of cubic (Ba0.5Ca0.5)(Fe0.5Mg0.5)O3- heated in CO2 up to 600 °C, and a pair of sextets of tetrahedral FeIII (Hin = 43 T) and octahedral FeIII (Hin = 51 T) were produced above 800 °C, and an additional sextet characteristic of FeIII in a spinel structure (Hin = 48 T) was observed at 1000 °C. On the other hand, a pair of sextets of tetrahedral and octahedral FeIII of the orthorhombic (Ca0.95Ba0.05)(Fe0.5Mg0.5)O3- showed hardly any change after absorption of CO2. It is concluded that only a small portion of Mg entered the orthorhombic phase of (Ca0.95Ba0.05)(Fe,Mg)O3- and Mg preferred the octahedral B site of the perovskite lattice. The excess Mg formed separate CaO-MgO mixed oxide, and the primary mechanism of CO2-trapping is the formation of CaMg(CO3)2.
Authors:L. Bertelli, A. Puerta, M. Wrenn, and J. Lipsztein
Literature data from in vivo chest measurements and urinary excretion rates of individuals exposed to U3O8 and UO2 were used to compare the results predicted by different models with empirical observations in humans. As a result the use of the respiratory tract model proposed in ICRP Publication 66 with its default absorption parameters underestimates urinary excretion of inhaled U3O8 and UO2. The new respiratory tract model also overpredicts the Fecal/Urine activity ratio, independently of the systemic model. For U3O8 and UO2 the choice of systemic model has very little influence on the predicted urinary excretion of inhaled compounds. On the other way, the choice of the respiratory tract model does influence the predicted urinary excretion significantly. In this work specific absorption parameters for U3O8 and UO2 were derived to be used in the respiratory tract model proposed in ICRP Publication 66. The predicted biokinetics of these compounds were compared with those derived for Type M and Type S compounds of uranium.
Authors:M. Rakszegi, G. Balázs, F. Békés, A. Harasztos, A. Kovács, L. Láng, Z. Bedő, and S. Tömösközi
Damaged starch, protein and arabinoxylan (AX) content and composition have been related to water absorption (WA) in a large set of samples. We tested 20 modern bread wheat cultivars bred in Hungary, 20 old Hungarian landraces, and 17 cultivars with special biochemical/functional characteristics from all around the world, this last set for international comparison. Grain was field grown in the 2011 and 2012 harvest seasons. Alinear mathematical model has been developed to estimate WA from protein content, starch damage, AX content and the relative amount of soluble proteins with strong correlation (r2 = 0.65) between measured and estimated data. The introduction of a new parameter, related to the cultivar dependent quantitative composition of soluble proteins and determined by lab-on-a-chip (LOC) analysis, largely improved the predictability of WA. Based on the large variation among the level of AX and certain soluble protein components in wheat flour and their significant contribution toWA determination, it was concluded, that these properties could be appropriate target traits to alter them during wheat breeding programs to improve the WA of wheat flour.
Authors:T. Ito, T. Nagasaki, K. Iwasaki, M. Yoshino, and T. Matsui
Summary Proton concentration in SrZr0.95M0.05O3-α (M=Ga, Sc, Y and Nd) was measured with a thermobalance at different temperatures (T=673-973 K) and water vapor pressures (PH2O=0.9-12.8 kPa). At all the pressures and temperatures examined, the amount of proton concentration in these samples is in the order of Sc>Y>Ga>Nd. By an equilibrium evaluation, we estimated the maximum possible proton concentration about 2.0 mol% in these samples. Infrared (IR) absorption spectra are measured in these samples. The absorption bands can be fitted by four (M=Ga, Y, Nd) or three (M=Sc) Gaussian bands.
Authors:N. Talaie, H. Aghabozorg, and S. Alamdar Milani
In this research, for the first time Nb and Ge were doped into titanosilicate nanoparticles up to 25% simultaneously. Crystalline
phases and morphology of the synthesized samples were studied by X-ray diffraction (XRD) method and scanning electron microscope
(SEM), respectively. Elemental analysis of the samples was performed using X-ray fluorescence (XRF) and Energy dispersive
X-ray (EDX) techniques. Surface area of the samples was measured by BET method. Ion exchange potential of the synthesized
samples for Sr2+ and Cs+ and effective parameters such as concentration, temperature, time, and pH were investigated. In addition,137Cs and 90Sr radio nuclides absorption in the best appropriate sample was examined. The selectivity of the samples for absorption of
137Cs and 90Sr was studied by gamma spectroscopy, liquid scintillation spectrometry, and atomic absorption spectroscopy methods. The obtained
results showed that the prepared samples had good potential for absorption of 137Cs and 90Sr from the model solution. The sample containing equal amount of niobium and germanium, removed completely the 137Cs within the waste water of Tehran nuclear reactor and 90Sr in the desired solution.
Authors:M. Morán-Pineda, S. Castillo, M. Asomoza, and R. Gómez
TG, FTIR-(CO absorption), and catalytic activity in the NO reduction by CO were used to characterize Cu/Al2O3-TiO2 catalysts prepared by co-gelling aluminum tri-sec-butoxide and titanium iso-propoxide at pH 9 and at pH 3 gelling conditions.
Under nitrogen flow, copper oxide decomposition, oxygen storage capacity (OSC) and sample dehydroxylation (total mass loss)
was followed by TG. The CuO decomposition forming Cu0, Cu+1 was observed by means of FTIR (CO absorption) spectra. In pH 9 sample the large amount of Cu0 was observed. At low total mass loss and high Cu0/Cu+1+Cu+2 ratio (pH 9 sample) a lowest light-off in the NO reduction by CO was observed.