Assessment of the necessity of cooling of the Stirling engine expansion piston

Heat balance of the Stirling engine expansion piston is investigated. This balance considers heat flows that are applied to the expansion piston from outside parts, generated by friction in the piston-liner contact zone, and rejected to the cooling medium. The average heat transfer coefficient is obtained by means of division of a predicted value of the thermal conductance by cooled area of the expansion piston. Dimensionless variables are derived from an expression for determination of the thermal conductance, and the dimensionless chart is presented

The splice variants of UBF differentially regulate RNA polymerase I transcription elongation in response to ERK phosphorylation

The mammalian architectural HMGB-Box transcription factor UBF is ubiquitously expressed in two variant forms as the result of a differential splicing event, that in the UBF2 deletes 37 amino acid from the second of six HMGB-boxes. Several attempts to define a function for this shorter UBF2 protein have been less than satisfactory. However, since all mammals appear to display similar levels of the longer and shorter UBF variants, it is unlikely that UBF2 is simply nonfunctional. Previously we showed that phosphorylation of UBF by the MAP-kinase ERK regulates chromatin folding and transcription elongation, explaining the rapid response of the ribosomal RNA genes to growth factors. Here we have investigated the roles the UBF variants play in the response of these genes to ERK activity. We demonstrate that the variant HMGB-box 2 of UBF2 has lost the ability to bind bent DNA and hence to induce chromatin folding. As a result it is significantly less effective than UBF1 at arresting RNAPI elongation but at the same time is more responsive to ERK phosphorylation. Thus, UBF2 functionally simulates a hemi-phosphorylated UBF whose expression may provide a means by which to tune the response of the ribosomal RNA genes to growth factor stimulation

Phantasmagorias in Uganda

Internship in Western Uganda during August of 2018https://deepblue.lib.umich.edu/bitstream/2027.42/148307/1/NathanStefanovskyLelaHickonbottom.pd

Zirconolite polytypes and murataite polysomes in matrices for the REE-actinide fraction of HLW

Electron backscatter diffraction (EBSD) has been used for more than 30 years for analyzing the structure of minerals and artificial substances. In recent times, EBSD has been widely applied for investigation of irradiated nuclear fuel and matrices for the immobilization of radioactive waste. The combination of EBSD and scanning electron microscopy (SEM/EDS) methods allows researchers to obtain simultaneously data on a specimen's local composition and structure. The article discusses the abilities of SEM/EDS and EBSD techniques to identify zirconolite polytype modifications and members of the polysomatic murataite-pyrochlore series in polyphase ceramic matrices, with simulations of Pu (Th) and the REE-actinide fraction (Nd) of high-level radioactive waste

The cellular abundance of the essential transcription termination factor TTF-I regulates ribosome biogenesis and is determined by MDM2 ubiquitinylation

The ARF tumour suppressor stabilizes p53 by negatively regulating the E3 ubiquitin ligase MDM2 to promote cell cycle arrest and cell death. However, ARF is also able to arrest cell proliferation by inhibiting ribosome biogenesis. In greater part this is achieved by targeting the transcription termination factor I (TTF-I) for nucleolar export, leading to an inhibition of both ribosomal RNA synthesis and processing. We now show that in the absence of ARF, TTF-I is ubiquitinylated by MDM2. MDM2 interacts directly with TTF-I and regulates its cellular abundance by targeting it for degradation by the proteasome. Enhanced TTF-I levels inhibit ribosome biogenesis by suppressing ribosomal RNA synthesis and processing, strongly suggesting that exact TTF-I levels are critical for efficient ribosome biogenesis. We further show that concomitant with its ability to displace TTF-I from the nucleolus, ARF inhibits MDM2 ubiquitinylation of TTF-I by competitively binding to a site overlapping the MDM2 interaction site. Thus, both the sub-nuclear localization and the abundance of TTF-I are key regulators of ribosome biogenesis

The Effect of Waste Loading and Glass Structural Factors on Structure and Chemical Durability of SB2 and SB4 SRS Waste Glasses -11397

ABSTRACT Glassy materials simulating vitrified high-Na/Fe (Sludge Batch 2 -SB2) and high-Na/Fe/Al (Sludge Batch 4 -SB4) Savannah River Site high level wastes (HLW) were produced in a resistive furnace and 236 and 418 mm inner diameter cold crucibles. The effect of waste loading (WL) and glass structural factors (degree of connectedness of glass network, metal oxides to boron oxide ratios) on chemical durability of glassy materials was studied

Summary Of Cold Crucible Vitrification Tests Results With Savannah River Site High Level Waste Surrogates

The cold crucible inductive melting (CCIM) technology successfully applied for vitrification of low- and intermediate-level waste (LILW) at SIA Radon, Russia, was tested to be implemented for vitrification of high-level waste (HLW) stored at Savannah River Site, USA. Mixtures of Sludge Batch 2 (SB2) and 4 (SB4) waste surrogates and borosilicate frits as slurries were vitrified in bench- (236 mm inner diameter) and full-scale (418 mm inner diameter) cold crucibles. Various process conditions were tested and major process variables were determined. Melts were poured into 10L canisters and cooled to room temperature in air or in heat-insulated boxes by a regime similar to Canister Centerline Cooling (CCC) used at DWPF. The products with waste loading from ~40 to ~65 wt.% were investigated in details. The products contained 40 to 55 wt.% waste oxides were predominantly amorphous; at higher waste loadings (WL) spinel structure phases and nepheline were present. Normalized release values for Li, B, Na, and Si determined by PCT procedure remain lower than those from EA glass at waste loadings of up to 60 wt.%

Ion-beam-induced amorphization and order-disorder transition in the murataite structure

Murataite (A3B6C2O22−x/2,F3m)(A3B6C2O22−x∕2,F4¯3m), a derivative of an anion-deficient fluorite structure, has been synthesized as different polytypes as a result of cation ordering. Ion-beam-induced amorphization has been investigated by 1-MeV1-MeV Kr2+Kr2+ ion irradiation with in situ transmission electron microscopy. The critical amorphization dose was determined as a function of temperature and the degree of structural disordering. A lower critical amorphization temperature ( ∼ 860 K)(∼860K) was obtained for the disordered murataite as compared with that of the murataite superstructure (930 to 1060 K)(930to1060K). An ion-beam-induced ordered murataite to a disordered fluorite transition occurred in the murataite superstructure, similar to that observed in the closely related pyrochlore structure-type, A2B2O7A2B2O7. The ion-beam-induced defect fluorite structure is more energetically stable in the murataite structure with a higher degree of structural disordering, as compared with the murataite superstructure. This suggests that the degree of intrinsic structural disorder has a significant effect on the energetics of structural disordering process; this affects the tendency toward the order-disorder structural transition for fluorite-related compounds and their response to ion-beam-induced amorphization.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87577/2/113536_1.pd

Synthesis and characterisation of brannerite compositions (U0.9Ce0.1)(1-x)MxTi2O6 (M = Gd3+, Ca2+) for the immobilisation of MOX residues

A suite of uranium brannerites for the disposal of MOX residues, formulated (U0.9Ce0.1)1−xMxTi2O6 (M = Ca2+ and/or Gd3+), were prepared using a mixed oxide route under oxidising, inert and reducing atmospheres (air, argon and H2/N2). Gd3+ was added to act as a neutron absorber in the final Pu bearing wasteform and Ce added to function as a structural analogue for Pu. X-ray powder diffraction of the synthesised specimens found that phase distribution was strongly affected by the processing atmosphere and Gd content. In all cases prototypical brannerite was formed, accompanied by different secondary phases dependent on processing atmosphere. Microstructural analysis (SEM) of the sintered samples confirmed the results of the X-ray powder diffraction. Bulk XANES found that Ti remained in the Ti4+ oxidation state whereas Ce was uniformly reduced to the Ce3+ oxidation state regardless of processing conditions or stoichiometry. Micro-focus XANES was used to determine U oxidation in the brannerite phase and showed that U oxidised to higher U oxidation states to charge compensate. It was concluded that the charge balance mechanism was a combination of U oxidation and A-site vacancies