Oil Transportation in Pipelines with the Existence of Ice

PresentationWhen the ambient temperature is below freezing point, ice may form in the oil transportation pipelines, which can cause flow assurance issues, such as restricting flow path or even plugging the pipeline. Ice plugging was reported to delay the restart of the Poplar pipeline system gathering crude oil from Montana and North Dakota. [1] Ice may also pose threats to the Trans-Alyeska Pipeline System (TAPS). The declining throughput makes the oil get colder much faster. If oil temperature falls below the freezing point, ice forms and leads to flow assurance issues, such as coating critical valves, accumulating in the pipeline, and restricting flow. [2] This paper investigates the fundamentals of ice formation in the pipeline and its effect on the transportation system. A 2-inch diameter carbon steel flow loop was instrumented to measure pressure, temperature, and differential pressure. The experimental results show that ice formation can restrict flow at the low sport in front of the flow meter, the inserted thermocouples, and the perforated plate. Annular ice deposition was found at the pipe wall. The morphology of the deposition is rime ice, indicating the deposition is due to small ice crystals sticking to the pipe surface. It was found that the formation of annular deposition requires a negative temperature gradient. The effect of water cuts and fluid properties on plugging tendency is discussed. The mechanisms for ice deposition along the pipe and plugging at the pipe components are proposed

Clinical and magnetic resonance imaging characteristics of thoracolumbar intervertenral disk extrusions and protrusions in large breed dogs

It has recently been shown that the fat-derived hormone adiponectin has the ability to decrease hyperglycemia and to reverse insulin resistance. However, bacterially produced full-length adiponectin is functionally inactive. Here, we show that endogenous adiponectin secreted by adipocytes is post-translationally modified into eight different isoforms, as shown by two-dimensional gel electrophoresis. Carbohydrate detection revealed that six of the adiponectin isoforms are glycosylated. The glycosylation sites were mapped to several lysines (residues 68, 71, 80, and 104) located in the collagenous domain of adiponectin, each having the surrounding motif of GXKGE(D). These four lysines were found to be hydroxylated and subsequently glycosylated. The glycosides attached to each of these four hydroxylated lysines are possibly glucosylgalactosyl groups. Functional analysis revealed that full-length adiponectin produced by mammalian cells is much more potent than bacterially generated adiponectin in enhancing the ability of subphysiological concentrations of insulin to inhibit gluconeogenesis in primary rat hepatocytes, whereas this insulin-sensitizing ability was significantly attenuated when the four glycosylated lysines were substituted with arginines. These results indicate that full-length adiponectin produced by mammalian cells is functionally active as an insulin sensitizer and that hydroxylation and glycosylation of the four lysines in the collagenous domain might contribute to this activity.link_to_subscribed_fulltex

Novel heterochronic functions of the Caenorhabditis elegans period-related protein LIN-42

AbstractLIN-42, the Caenorhabditis elegans homolog of the Period (Per) family of circadian rhythm proteins, functions as a member of the heterochronic pathway, regulating temporal cell identities. We demonstrate that lin-42 acts broadly, timing developmental events in the gonad, vulva, and sex myoblasts, in addition to its well-established role in timing terminal differentiation of the hypodermis. In the vulva, sex myoblasts, and hypodermis, lin-42 activity prevents stage-specific cell division patterns from occurring too early. This general function of timing stage-appropriate cell division patterns is shared by the majority of heterochronic genes; their mutation temporally alters stage-specific division patterns. In contrast, lin-42 function in timing gonad morphogenesis is unique among the known heterochronic genes: inactivation of lin-42 causes the elongating gonad arms to reflex too early, a phenotype which implicates lin-42 in temporal regulation of cell migration. Three additional isoforms of lin-42 are identified that expand our view of the lin-42 locus and significantly extend the homology between LIN-42 and other PER family members. We show that, similar to PER proteins, LIN-42 has a dynamic expression pattern; its levels oscillate relative to the molts during postembryonic development. Transformation rescue studies indicate lin-42 is bipartite with respect to function. Intriguingly, the hallmark PAS domain is dispensable for LIN-42 function in transgenic animals

Galactic Gamma-Ray Background Radiation from Supernova Remnants

The contribution of the Source Cosmic Rays (SCRs), confined in Supernova Remnants, to the diffuse high energy \gr emission above 1 GeV from the Galactic disk is studied. \grs produced by the SCRs have a much harder spectrum compared with those generated by the Galactic Cosmic Rays which occupy a much larger residence volume uniformly. SCRs contribute less than 10% at GeV energies and become dominant at \gr energies above 100 GeV. The contributions from $\pi^0$-decay and Inverse Compton \grs have comparable magnitude and spectral shape, whereas the Bremsstrahlung component is negligible. At TeV energies the contribution from SCRs increases the expected diffuse \gr flux almost by an order of magnitude. It is shown that for the inner Galaxy the discrepancy between the observed diffuse intensity and previous model predictions at energies above a few GeV can be attributed to the SCR contribution.Comment: 25 pages, 1 figures, to appear in Ap

Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Foreground Polarization

We present a full-sky model of polarized Galactic microwave emission based on three years of observations by the Wilkinson Microwave Anisotropy Probe (WMAP) at frequencies from 23 to 94 GHz. The model compares maps of the Stokes Q and U components from each of the 5 WMAP frequency bands in order to separate synchrotron from dust emission, taking into account the spatial and frequency dependence of the synchrotron and dust components. This simple two-component model of the interstellar medium accounts for at least 97% of the polarized emission in the WMAP maps of the microwave sky. Synchrotron emission dominates the polarized foregrounds at frequencies below 50 GHz, and is comparable to the dust contribution at 65 GHz. The spectral index of the synchrotron component, derived solely from polarization data, is -3.2 averaged over the full sky, with a modestly flatter index on the Galactic plane. The synchrotron emission has mean polarization fraction 2--4% in the Galactic plane and rising to over 20% at high latitude, with prominent features such as the North Galactic Spur more polarized than the diffuse component. Thermal dust emission has polarization fraction 1% near the Galactic center, rising to 6% at the anti-center. Diffuse emission from high-latitude dust is also polarized with mean fractional polarization 0.036 +/- 0.011.Comment: 9 pages with 8 figures. For higher quality figures, see the version posted at http://lambda.gsfc.nasa.gov/product/map/dr2/map_bibliography.cf

Magnetoelastic properties and behaviour of 4C pyrrhotite, Fe7S8, through the Besnus transition

Pyrrhotite, Fe7S8, is a commonly occurring carrier of magnetic remanence and has a low temperature transition, the Besnus transition, involving a change in spin state. Variations of the thermodynamic, magnetic and elastic properties through this transition at ~33 K in a natural sample of 4C pyrrhotite have been tested against a group theoretical model for coupling between order parameters relating to Fe/vacancy ordering (irrep U 1(1/2,0,1/4)) and magnetic ordering (irreps m${{\Gamma}}_{4}^{+}$ and m${{\Gamma}}_{5}^{+}$). Magnetoelastic coupling is weak but the pre-existing microstructure of ferroelastic and magnetic domains, that develop as a consequence of Fe/vacancy and ferrimagnetic ordering during slow cooling in nature (P63/mmc → C2'/c'), causes subtle changes in the low temperature transition (C2'/c' → P $\overline{1}$). The Besnus transition involves a rotation of magnetic moments out of the a–c plane of the monoclinic structure, but it appears that the transition temperature might vary locally according to whether it is taking place within the pre-existing domain walls or in the domains that they separate. Evidence of metamagnetic transitions suggests that the magnetic field–temperature phase diagram will display some interesting diversity. Low temperature magnetic transitions in minerals of importance to the palaeomagnetism community have been used to identify the presence of magnetite and haematite in rocks and the Besnus transition is diagnostic of the existence of pyrrhotite, Fe7S8