Revisiting the U-238 thermal capture cross section and gamma-raymission probabilities from Np-239 decay

The precise value of the thermal capture cross section of238U is uncertain, and evaluated cross sections from various sourcesdiffer by more than their assigned uncertainties. A number of theoriginal publications have been reviewed to assess the discrepant data,corrections were made for more recent standard cross sections andotherconstants, and one new measurement was analyzed. Due to the strongcorrelations in activation measurements, the gamma-ray emissionprobabilities from the beta decay of 239Np were also analyzed. As aresult of the analysis, a value of 2.683 +- 0.012 barns was derived forthe thermal capture cross section of 238U. A new evaluation of thegamma-ray emission probabilities from 239Np decay was alsoundertaken

Analyses of Oxyanion Materials by Prompt Gamma Activation Analysis

Prompt gamma activation analysis (PGAA) has been used to analyze metal ion oxyanion materials that have multiple applications, including medicine, materials, catalysts, and electronics. The significance for the need for accurate, highly sensitive analyses for the materials is discussed in the context of quality control of end products containing the parent element in each material. Applications of the analytical data for input to models and theoretical calculations related to the electronic and other properties of the materials are discussed

A Large Expansion of the HSFY Gene Family in Cattle Shows Dispersion across Yq and Testis-Specific Expression

Heat shock transcription factor, Y-linked (HSFY) is a member of the heat shock transcriptional factor (HSF) family that is found in multiple copies on the Y chromosome and conserved in a number of species. Its function still remains unknown but in humans it is thought to play a role in spermatogenesis. Through real time polymerase chain reaction (PCR) analyses we determined that the HSFY family is largely expanded in cattle (∼70 copies) compared with human (2 functional copies, 4 HSFY-similar copies). Unexpectedly, we found that it does not vary among individual bulls as a copy number variant (CNV). Using fluorescence in situ hybridization (FISH) we found that the copies are dispersed along the long arm of the Y chromosome (Yq). HSFY expression in cattle appears restricted to the testis and its mRNA correlates positively with mRNA markers of spermatogonial and spermatocyte cells (UCHL1 and TRPC2, respectively) which suggests that HSFY is expressed (at least in part) in early germ cells

Thermal neutron capture cross sections for O 16,17,18 and H 2

Thermal neutron capture γ-ray spectra for O16,17,18 and H2 have been measured with guided cold neutron beams from the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) reactor and the Budapest Research Reactor (BRR) on natural and O17,18 enriched D2O targets. Complete neutron capture γ-ray decay schemes for the O16,17,18(n,γ) reactions were measured. Absolute transition probabilities were determined for each reaction by a least-squares fit of the γ-ray intensities to the decay schemes after accounting for the contribution from internal conversion. The transition probability for the 870.76-keV γ ray from O16(n,γ) was measured as Pγ(871)=96.6 ±0.5% and the thermal neutron cross section for this γ ray was determined as 0.164±0.003 mb by internal standardization with multiple targets containing oxygen and stoichiometric quantities of hydrogen, nitrogen, and carbon whose γ-ray cross sections were previously standardized. The γ-ray cross sections for the O17,18(n,γ) and H2(n,γ) reactions were then determined relative to the 870.76-keV γ-ray cross section after accounting for the isotopic abundances in the targets. We determined the following total radiative thermal neutron cross sections for each isotope from the γ-ray cross sections and transition probabilities; σ0(O16)=0.170±0.003 mb; σ0(O17)=0.67±0.07 mb; σ0(O18)=0.141±0.006 mb; and σ0(H2)=0.489±0.006 mb

Thermal neutron radiative cross sections for Li 6,7, Be 9, B 10,11, C 12,13, and N 14,15

Total thermal radiative neutron cross sections have been measured on natural and enriched isotopic targets containing Li6,7,Be9,B10,11,C12,13, and N14,15 with neutron beams from the Budapest Reactor. Complete neutron capture γ-ray decay schemes were measured for each isotope. Absolute transition probabilities have been determined by a least-squares fit of the transition intensities, corrected for internal conversion, to the (n,γ) decay schemes. The γ-ray cross sections were standardized using stoichiometric compounds containing both the isotope of interest and another element whose γ-ray cross sections are well known. Total cross sections σ0 were then determined for each isotope from the γ-ray cross sections and transition probabilities. For the B11(n,γ)B12 reaction decay transition probabilities were determined for the γ rays from B12 (t1/2=20.20 ms) β- decay

Thermal neutron capture cross sections for O 16,17,18 and H 2

Thermal neutron capture γ-ray spectra for O16,17,18 and H2 have been measured with guided cold neutron beams from the Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRM II) reactor and the Budapest Research Reactor (BRR) on natural and O17,18 enriched D2O targets. Complete neutron capture γ-ray decay schemes for the O16,17,18(n,γ) reactions were measured. Absolute transition probabilities were determined for each reaction by a least-squares fit of the γ-ray intensities to the decay schemes after accounting for the contribution from internal conversion. The transition probability for the 870.76-keV γ ray from O16(n,γ) was measured as Pγ(871)=96.6 ±0.5% and the thermal neutron cross section for this γ ray was determined as 0.164±0.003 mb by internal standardization with multiple targets containing oxygen and stoichiometric quantities of hydrogen, nitrogen, and carbon whose γ-ray cross sections were previously standardized. The γ-ray cross sections for the O17,18(n,γ) and H2(n,γ) reactions were then determined relative to the 870.76-keV γ-ray cross section after accounting for the isotopic abundances in the targets. We determined the following total radiative thermal neutron cross sections for each isotope from the γ-ray cross sections and transition probabilities; σ0(O16)=0.170±0.003 mb; σ0(O17)=0.67±0.07 mb; σ0(O18)=0.141±0.006 mb; and σ0(H2)=0.489±0.006 mb

Microstructural characterization of PEMs based on sulfonated syndiotactic polystyrene in the delta co-crystalline phase

Syndiotactic polystyrene (s-PS) is able to form different kinds of co-crystalline phases with guest molecules of various size, shape and property. Several advanced materials have been produced starting from s-PS co-crystalline films [1-2]. In particular, sulfonated s-PS (s-SPS) can be used as proton-conductive membrane for fuel cells, as it presents high proton conductivity (comparable with Nafion). Besides, it shows a high chemical and thermo-mechanical stability and a low cost [3]. The morphology of different s-PS clathrates and the structural behavior of s-SPS upon hydration can be more thoroughly understood by combining X-rays scattering and FT-IR with SANS [4]. In fact, exploiting the neutron contrast variation between various hydrogenated and deuterated components of s-PS and s-SPS clathrates, additional and unique information about the distribution of guest molecules in the crystalline and amorphous regions and about the hydrated domains of the polymer were obtained. Moreover, the stretching of films leads to occurrence and distribution of scattering features from typical morphologies on specific directions and sectors of detection plan, which enables an accurate structural study of such complex polymeric systems. A complete SANS investigation on s-PS samples, starting from their crystallization with guest molecules to the subsequent sulfonation and hydration, was performed at SANS diffractometer KWS2 of MLZ. This experimental analysis has highlighted that the morphology of these polymeric films is characterized by hydrated channels in the amorphous phase alternated to staples of crystalline lamellae, along the stretching direction.[1]. J. Schellenberg in “Syndiotactic Polystyrene’’, John Wiley & Sons, Inc. 2010. [2]. G. Guerra et al., J. of Pol. Sci. B, Polymer Physics 2012, 50, 305.[3]. G. Fasano et al., Int. Journal. of Hydrogen Energy 2013, 36, 8038.[4]. F. Kaneko et al., Polymer 2013, 54, 3145 and Chemistry Letters, 2015, Accepted