Double universality of the transition in the supercritical state

Universality aids consistent understanding of physical properties and states of matter where a theory predicts how a property of a phase (solid, liquid, and gas) changes with temperature or pressure. Here, we show that the matter above the critical point has a remarkable double universality. The first universality is the transition between the liquid-like and gas-like states seen in the crossover of the specific heat on the dynamical length with a fixed inversion point. The second universality is the operation of this effect in many supercritical fluids, including N(2), CO(2), Pb, H(2)O, and Ar. Despite different structure and chemical bonding, the transition has the same fixed inversion point deep in the supercritical state. This advances our understanding of the supercritical state previously considered to be a featureless area on the phase diagram and a theoretical guide for improved deployment of supercritical fluids in green and environmental applications

Microscopic Structure of Liquid Nitric Oxide

The microscopic structure of nitric oxide is investigated using neutron scattering experiments. The measurements are performed at various temperatures between 120 and 144 K and at pressures between 1.1 and 9 bar. Using the technique of empirical potential structure refinement (EPSR), our results show that the dimer is the main form, around 80%, of nitric oxide in the liquid phase at 120 K, but the degree of dissociation to monomers increases with increasing temperature. The reported degree of dissociation of dimers, and its trend with increasing temperature, is consistent with earlier measurements and studies. It is also shown that nonplanar dimers are not inconsistent with the diffraction data and that the possibility of nitric oxide molecules forming longer oligomers, consisting of bonded nitrogen atoms along the backbone, cannot be ruled out in the liquid. A molecular dynamics simulation is used to compare the present EPSR simulations with an earlier proposed intermolecular potential for the liquid

Development of electromagnetic analysis methods for large aperture antennas

Both deterministic and statistical analysis methods for investigating large aperture antenna radiation patterns are examined. The effects of surface errors on radiation patterns are discussed

Experimental and modelling evidence for structural crossover in supercritical CO₂

Physics of supercritical state is understood to a much lesser degree compared to subcritical liquids. Carbon dioxide in particular has been intensely studied, yet little is known about the supercritical part of its phase diagram. Here, we combine neutron scattering experiments and molecular dynamics simulations and demonstrate the structural crossover at the Frenkel line. The crossover is seen at pressures as high as 14 times the critical pressure and is evidenced by changes of the main features of the structure factor and pair distribution functions

Universal interrelation between dynamics and thermodynamics and a dynamically driven “c” transition in fluids

Our very wide survey of the supercritical phase diagram and its key properties reveals a universal interrelation between dynamics and thermodynamics and an unambiguous transition between liquidlike and gaslike states. This is seen in the master plot showing a collapse of the data representing the dependence of specific heat on key dynamical parameters in the system for many different paths on the phase diagram. As a result, the observed transition is path independent. We call it a “c” transition due to the c-shaped curve parametrizing the dependence of the specific heat on key dynamical parameters. The c transition has a fixed inversion point and provides a new structure to the phase diagram, operating deep in the supercritical state (up to, at least, 2000 times the critical pressure and 50 times the critical temperature). The data collapse and path independence as well as the existence of a special inversion point on the phase diagram are indicative of either of a sharp crossover or a new phase transition in the deeply supercritical state

Hypertension in response to IL-6 during pregnancy: role of AT1-receptor activation

BACKGROUND: Increases in interleukin 6 (IL-6) and agonistic autoantibodies to the angiotensin II type 1 receptor (AT1-AA) are proposed to be important links between placental ischemia and hypertension in preeclampsia. METHODS: The purpose of this study was to determine whether IL-6 (5 ng/day), infused into normal pregnant (NP) rats, increased mean arterial pressure (MAP) and AT1-AA. MAP was analyzed in the presence and absence of an angiotensin type 1 receptor (AT1R) antagonist, losartan, L. RESULTS: MAP and AT1-AA increased from 102 ± 2 to 118 ± 4 mmHg and 0.7 ± 0.3 NP to 14.1 ± 1.4 chronotropic units with chronic IL-6 infusion. MAP responses to IL-6 were abolished in losartan pretreated rats (85 ± 4 in NP + L vs 85 ± 3 mmHg in IL-6 + L). CONCLUSION: These data indicate that IL-6 stimulates AT1-AA and that activation of the AT1R mediates IL-6 induced hypertension during pregnancy

Palmitate and insulin synergistically induce IL-6 expression in human monocytes

<p>Abstract</p> <p>Background</p> <p>Insulin resistance is associated with a proinflammatory state that promotes the development of complications such as type 2 diabetes mellitus (T2DM) and atherosclerosis. The metabolic stimuli that initiate and propagate proinflammatory cytokine production and the cellular origin of proinflammatory cytokines in insulin resistance have not been fully elucidated. Circulating proinflammatory monocytes show signs of enhanced inflammation in obese, insulin resistant subjects and are thus a potential source of proinflammatory cytokine production. The specific, circulating metabolic factors that might stimulate monocyte inflammation in insulin resistant subjects are poorly characterized. We have examined whether saturated nonesterified fatty acids (NEFA) and insulin, which increase in concentration with developing insulin resistance, can trigger the production of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in human monocytes.</p> <p>Methods</p> <p>Messenger RNA and protein levels of the proinflammatory cytokines IL-6 and TNF-α were measured by quantitative real-time PCR (qRT-PCR) and Luminex bioassays. Student's <it>t</it>-test was used with a significance level of <it>p </it>< 0.05 to determine significance between treatment groups.</p> <p>Results</p> <p>Esterification of palmitate with coenzyme A (CoA) was necessary, while β-oxidation and ceramide biosynthesis were not required, for the induction of IL-6 and TNF-α in THP-1 monocytes. Monocytes incubated with insulin and palmitate together produced more IL-6 mRNA and protein, and more TNF-α protein, compared to monocytes incubated with palmitate alone. Incubation of monocytes with insulin alone did not affect the production of IL-6 or TNF-α. Both PI3K-Akt and MEK/ERK signalling pathways are important for cytokine induction by palmitate. MEK/ERK signalling is necessary for synergistic induction of IL-6 by palmitate and insulin.</p> <p>Conclusions</p> <p>High levels of saturated NEFA, such as palmitate, when combined with hyperinsulinemia, may activate human monocytes to produce proinflammatory cytokines and support the development and propagation of the subacute, chronic inflammatory state that is characteristic of insulin resistance. Results with inhibitors of β-oxidation and ceramide biosynthesis pathways suggest that increased fatty acid flux through the glycerolipid biosynthesis pathway may be involved in promoting proinflammatory cytokine production in monocytes.</p

Dysregulation of the Intrarenal Vitamin D Endocytic Pathway in a Nephropathy-Prone Mouse Model of Type 1 Diabetes

Microalbuminuria in humans with Type 1 diabetes (T1D) is associated with increased urinary excretion of megalin, as well as many megalin ligands, including vitamin-D-binding protein (VDBP). We examined the DBA/2J diabetic mouse, nephropathy prone model, to determine if megalin and VDBP excretion coincide with the development of diabetic nephropathy. Megalin, VDBP, and 25-hydroxy-vitamin D (25-OHD) were measured in urine, and genes involved in vitamin D metabolism were assessed in renal tissues from diabetic and control mice at 10, 15, and 18 weeks following the onset of diabetes. Megalin, VDBP, and 25-OHD were increased in the urine of diabetic mice. 1-α hydroxylase (CYP27B1) mRNA in the kidney was persistently increased in diabetic mice, as were several vitamin D-target genes. These studies show that intrarenal vitamin D handling is altered in the diabetic kidney, and they suggest that in T1D, urinary losses of VDBP may portend risk for intrarenal and extrarenal vitamin D deficiencies

Low-Speed Wind Tunnel Tests of Two Waverider Configuration Models

A definitive measurement of the low-speed flight characteristics of waverider-based aircraft is required to augment the overall design database for this important class of vehicles which have great potential for efficient high-speed flight. Two separate waverider-derived vehicles were tested; one in the 14- by 22-Foot Tunnel and the other in the 12-Foot Low Speed Tunnel at Langley Research Center. These tests provided measurements of moments and forces about all three axes, control effectiveness, flow field characteristics and the effects of configuration changes. The results of these tunnel tests are summarized and the subsonic aerodynamic characteristics of the two configurations are shown