Phase-field model for Hele-Shaw flows with arbitrary viscosity contrast. II. Numerical study

We implement a phase-field simulation of the dynamics of two fluids with arbitrary viscosity contrast in a rectangular Hele-Shaw cell. We demonstrate the use of this technique in different situations including the linear regime, the stationary Saffman-Taylor fingers and the multifinger competition dynamics, for different viscosity contrasts. The method is quantitatively tested against analytical predictions and other numerical results. A detailed analysis of convergence to the sharp interface limit is performed for the linear dispersion results. We show that the method may be a useful alternative to more traditional methods.Comment: 13 pages in revtex, 5 PostScript figures. changes: 1 reference added, figs. 4 and 5 rearrange

Phase-Field Formulation for Quantitative Modeling of Alloy Solidification

A phase-field formulation is introduced to simulate quantitatively microstructural pattern formation in alloys. The thin-interface limit of this formulation yields a much less stringent restriction on the choice of interface thickness than previous formulations and permits to eliminate non-equilibrium effects at the interface. Dendrite growth simulations with vanishing solid diffusivity show that both the interface evolution and the solute profile in the solid are well resolved

Single-Electron Spectroscopy

Contains research goals and objectives, reports on four research projects and a list of publications.Joint Services Electronics Program Contract DAAL03-92-C-0001Joint Services Electronics Program Grant DAAH04-95-1-0038National Science Foundation Young Investigator AwardPackard FoundationU.S. Navy - Office of Naval Researc

Evaluating the structure and magnitude of the ash plume during the initial phase of the 2010 Eyjafjallajökull eruption using lidar observations and NAME simulations

The Eyjafjallajökull volcano in Iceland erupted explosively on 14 April 2010, emitting a plume of ash into the atmosphere. The ash was transported from Iceland toward Europe where mostly cloud-free skies allowed ground-based lidars at Chilbolton in England and Leipzig in Germany to estimate the mass concentration in the ash cloud as it passed overhead. The UK Met Office's Numerical Atmospheric-dispersion Modeling Environment (NAME) has been used to simulate the evolution of the ash cloud from the Eyjafjallajökull volcano during the initial phase of the ash emissions, 14–16 April 2010. NAME captures the timing and sloped structure of the ash layer observed over Leipzig, close to the central axis of the ash cloud. Relatively small errors in the ash cloud position, probably caused by the cumulative effect of errors in the driving meteorology en route, result in a timing error at distances far from the central axis of the ash cloud. Taking the timing error into account, NAME is able to capture the sloped ash layer over the UK. Comparison of the lidar observations and NAME simulations has allowed an estimation of the plume height time series to be made. It is necessary to include in the model input the large variations in plume height in order to accurately predict the ash cloud structure at long range. Quantitative comparison with the mass concentrations at Leipzig and Chilbolton suggest that around 3% of the total emitted mass is transported as far as these sites by small (<100 μm diameter) ash particles

Three-year tracking of fatty acid composition of plasma phospholipids in healthy children

Objectives: The fatty acid composition of plasma phospholipids reflects the dietary fatty acid intake as well as endogenous turnover. We aimed at investigating the potential tracking of plasma phospholipid fatty acid composition in children that participated in a prospective cohort study. Methods: 26 healthy children participated in a longitudinal study on health risks and had been enrolled after birth. All children were born at term with birth weights appropriate for gestational age. Follow-up took place at ages 24, 36 and 60 months. At each time point a 24-hour dietary recall was obtained, anthropometric parameters were measured and a blood sample for phospholipid fatty acid analysis was taken. Results: Dietary intake of saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids at the three time points were not correlated. We found lower values for plasma MUFA and the MUFA/SFA ratio at 60 months compared to 24 months. In contrast, total PUFA, total n-6 and n-6 long-chain polyunsaturated fatty acids (LC-PUFA) were higher at 60 months. Significant averaged correlation coefficients (average of Pearson's R for 24 versus 36 months and 36 versus 60 months) were found for n-6 LC-PUFA (r = 0.67), n-6/n-3 LC-PUFA ratio (r = 0.59) and arachidonic acid/linoleic acid ratio (r = 0.64). Partial tracking was found for the docosahexaenoic acid/alpha-linolenic acid ratio (r = 0.33). Body mass index and sum of skinfolds Z-scores were similar in the three evaluations. Conclusions: A significant tracking of n-6 LC-PUFA, n-6 LC-PUFA/n-3 LC-PUFA ratio, arachidonic acid/ linoleic acid ratio and docosahexaenoic acid/alpha-linolenic acid ratio may reflect an influence of individual endogenous fatty acid metabolism on plasma concentrations of some, but not all, fatty acids. Copyright (c) 2007 S. Karger AG, Basel

In-beam internal conversion electron spectroscopy with the SPICE detector

The SPectrometer for Internal Conversion Electrons (SPICE) has been commissioned for use in conjunction with the TIGRESS $\gamma$-ray spectrometer at TRIUMF's ISAC-II facility. SPICE features a permanent rare-earth magnetic lens to collect and direct internal conversion electrons emitted from nuclear reactions to a thick, highly segmented, lithium-drifted silicon detector. This arrangement, combined with TIGRESS, enables in-beam $\gamma$-ray and internal conversion electron spectroscopy to be performed with stable and radioactive ion beams. Technical aspects of the device, capabilities, and initial performance are presented

Phase-field approach to heterogeneous nucleation

We consider the problem of heterogeneous nucleation and growth. The system is described by a phase field model in which the temperature is included through thermal noise. We show that this phase field approach is suitable to describe homogeneous as well as heterogeneous nucleation starting from several general hypotheses. Thus we can investigate the influence of grain boundaries, localized impurities, or any general kind of imperfections in a systematic way. We also put forward the applicability of our model to study other physical situations such as island formation, amorphous crystallization, or recrystallization.Comment: 8 pages including 7 figures. Accepted for publication in Physical Review

Sirtuin 1 in rat orthotopic liver transplantation: An IGL-1 preservation solution approach

© The Author(s) 2015. AIM: To investigate the possible involvement of Sirtuin 1 (SIRT1) in rat orthotopic liver transplantation (OLT), when Institute Georges Lopez 1 (IGL-1) preservation solution is enriched with trimetazidine (TMZ). METHODS: Male Sprague-Dawley rats were used as donors and recipients. Livers were stored in IGL-1 preservation solution for 8h at 4 °C, and then underwent OLT according to Kamada's cuff technique without arterialization. In another group, livers were stored in IGL-1 preservation solution supplemented with TMZ, at 10-6 mol/L, for 8 h at 4 °C and then underwent OLT. Rats were sacrificed 24 h after reperfusion, and liver and plasma samples were collected. Liver injury (transaminase levels), mitochondrial damage (glutamate dehydrogenase activity) oxidative stress (malondialdehyde levels), and nicotinamide adenine dinucleotide (NAD+), the co-factor necessary for SIRT1 activity, were determined by biochemical methods. SIRT1 and its substrates (ac-FoxO1, ac-p53), the precursor of NAD+, nicotinamide phosphoribosyltransferase (NAMPT), as well as the phosphorylation of adenosine monophosphate activated protein kinase (AMPK), p-mTOR, p-p70S6K (direct substrate of mTOR), autophagy parameters (beclin-1, LC3B) and MAP kinases (p-p38 and p-ERK) were determined by Western blot. RESULTS: Liver grafts preserved in IGL-1 solution enriched with TMZ presented reduced liver injury and mitochondrial damage compared with those preserved in IGL-1 solution alone. In addition, livers preserved in IGL-1 + TMZ presented reduced levels of oxidative stress. This was consistent with enhanced SIRT1 protein expression and elevated SIRT1 activity, as indicated by decreased acetylation of p53 and FoxO1. The elevated SIRT1 activity in presence of TMZ can be attributed to the enhanced NAMPT protein and NAD+/NADH levels. Up-regulation of SIRT1 was consistent with activation of AMPK and inhibition of phosphorylation of mTOR and its direct substrate (p-p70S6K). As a consequence, autophagy mediators (beclin-1 and LC3B) were overexpressed. Furthermore, MAP kinases were regulated in livers preserved with IGL-1 + TMZ, as they were characterized by enhanced p-ERK and decreased p-p38 protein expression. CONCLUSION: Our study shows that IGL-1 preservation solution enriched with TMZ protects liver grafts from the IRI associated with OLT, through SIRT1 up-regulation.Supported by Fondo de Investigaciones Sanitarias, No. FIS PI12/00519; and Eirini Pantazi is the recipient of a fellowship from AGAUR, No. 2012FI_B00382, Generalitat de Catalunya, Barcelona, Catalonia, Spain.Peer Reviewe

Continuous EB welding of the reinforcement of the CMS conductor

The Compact Muon Solenoid (CMS) is one of the general-purpose detectors to be provided for the LHC project at CERN. The design field of the CMS superconducting magnet is 4 T, the magnetic length is 12.5 m and the free bore is 6 m. In order to withstand the electro-mechanical forces during the operation of the CMS magnet, the superconducting cable embedded in a 99.998% pure aluminum matrix is reinforced with two sections of aluminum alloy EN AW-6082 assembled by continuous Electron Beam Welding (EBW). A dedicated production line has been designed by Techmeta, a leading company in the field of EBW. The production line has a total length of 70 m. Non-stop welding of each of the 20 lengths of 2.5 km, required to build the coil, will last 22 hours. EBW is the most critical process involved in the production line. The main advantage of the EBW process is to minimize the Heat Affected Zone; this is particularly important for avoiding damage to the superconducting cable located only 4.7 mm from the welded joints. Two welding guns of 20 kW each operate in parallel in a vacuum chamber fitted with dynamic airlocks. After welding, the conductor is continuously machined on the four faces and on each corner to obtain the required dimensions and surface finish. Special emphasis has been put on quality monitoring. All significant production parameters are recorded during operation and relevant samples are taken from each produced length for destructive testing purposes. In addition, a continuous phased array ultrasonic checking device is located immediately after the welding unit for the continuous welding quality control, along with a dimension laser measurement unit following the machining. (8 refs)