Enhanced dissipation and transition threshold for the poiseuille flow in a periodic strip

We consider the solution to the two-dimensional Navier–Stokes equations around the Poiseuille flow (y²,0) on T x R with small viscosity v > 0 . Via a hypocoercivity argument, we prove that the -dependent modes of the solution to the linear problem undergo the enhanced dissipation effect with a rate proportional to v^1/2 . Moreover, we study the nonlinear enhanced dissipation effect and we establish a transition threshold of v^2/3+ for initial data in L² . Namely, when the L² norm of the perturbation of the Poiseuille flow is size at most v^2/3+ , its size remains so for all times and the enhanced dissipation persists with a rate proportional to v^1/2

Energy Enhancement of Solid Recovered Fuel within Systems of Conventional Thermal Power Generation

Abstract The main objective of this article is to verify the feasibility, in terms of technical and economical issues, of a new refuse-derived fuel SRF (Solid Recovered Fuel) to be used as a new fuel in a thermal power station or in an incineration plants. By means of the innovative micronization technology it is possible to produce SRF suitable for the technical specifications of the plants which, taking into account appropriate modifications, could be reconverted and not decommissioned. The present energy supply scenario shows a partial contraction of the activities of power plant thermal generation despite an increase of the power demand and despite one of the highest energy cost in Europe. It is likely to surmise a gradual stall of such activities and finally the decommissioning due to the fact that plants will turn out to be not economically productive. On the other hand, it is now necessary to promote adequate policies for sustainable waste management. An opportunity in this sense is represented by the smart usage (made possible through innovative manufacturing processes) of the SRF as an energy source. The tests conducted on the innovative chemical-mechanical micronization technology showed an average energetic cost of 30 kWh/ton, and an average production cost of 15 €/ton for the 0.5 mm size. Combustion tests showed a good environmental and combustion performance. In this article, the refuse-derived fuel (which is governed according to the Decrees of the Ministry of Environment, Land and Sea) has been obtained through an innovative technology of chemical-mechanical micronization. We have also proceeded to verify the functional feasibility of the fuel production in order to feed incinerators and power plants in partial or total substitution of the conventional fuels (coal, fuel oil)

Assessment of Natural Resources Use for Sustainable Development - DPSIR Framework for Case Studies in Portsmouth and Thames Gateway, U.K.

This chapter reports on the uses of the DPSIR framework to assess the sustainability of the intertidal environments within the two UK case study areas, Portsmouth and Thames Gateway. It focuses on statutory conservation areas dominated by intertidal habitats. Two are located in Portsmouth (Portsmouth and Langstone Harbours) and four in the Thames Gateway (Benfleet Marshes, South Thames Estuary, Medway Estuary and the Swale in the Thames Gateway). Based on the reduction of a number of pressures and impacts observed in recent decades and the improvement of overall environmental quality, all six SSSIs are considered to be sustainable in the short and medium term. In the future, it is possible that the impacts of climate change, especially sea-level rise, might result in further reduction in the area and/or quality of intertidal habitats. Further integration between conservation and planning objectives (both for urban development and management of flood risk) at local level is needed to support the long-term sustainability of intertidal habitats

Monitoring of the pre-equilibrium step in the alkyne hydration reaction catalyzed by au(Iii) complexes: A computational study based on experimental evidences

The coordination ability of the [(ppy)Au(IPr)]2+ fragment [ppy = 2-phenylpyridine, IPr = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene] towards different anionic and neutral X ligands (X = Cl 12, BF4 12, OTf 12, H2 O, 2-butyne, 3-hexyne) commonly involved in the crucial pre-equilibrium step of the alkyne hydration reaction is computationally investigated to shed light on unexpected experimental observations on its catalytic activity. Experiment reveals that BF4 12 and OTf 12 have very similar coordination ability towards [(ppy)Au(IPr)]2+ and slightly less than water, whereas the alkyne complex could not be observed in solution at least at the NMR sensitivity. Due to the steric hindrance/dispersion interaction balance between X and IPr, the [(ppy)Au(IPr)]2+ fragment is computationally found to be much less selective than a model [(ppy)Au(NHC)]2+ (NHC = 1,3-dimethylimidazol-2-ylidene) fragment towards the different ligands, in particular OTf 12 and BF4 12, in agreement with experiment. Effect of the ancillary ligand substitution demonstrates that the coordination ability of Au(III) is quantitatively strongly affected by the nature of the ligands (even more than the net charge of the complex) and that all the investigated gold fragments coordinate to alkynes more strongly than H2 O. Remarkably, a stabilization of the water-coordinating species with respect to the alkyne-coordinating one can only be achieved within a microsolvation model, which reconciles theory with experiment. All the results reported here suggest that both the Au(III) fragment coordination ability and its proper computational modelling in the experimental conditions are fundamental issues for the design of efficient catalysts

Islet adaptive changes to fructose-induced insulin resistance: β-cell mass, glucokinase, glucose metabolism, and insulin secretion

β-Cell mass, hexokinase/glucokinase (HK/GK) activity, glucose metabolism and insulin secretion were studied in the islets of rats with fructose-induced insulin resistance (IR). Normal male Wistar rats were fed a standard commercial diet and water without (control, C) or with 10% fructose-rich diet (FRD) for 3 weeks. Blood glucose (strips), triglyceride (commercial kit), and insulin (RIA) levels were measured at the time of death. Glucose-induced insulin release, glucose metabolism (14CO2 and 3H2O production from D-[U-14C]- and D-[5-3H]-glucose) and HK/GK activity (G-6-P production), transcription (RTPCR), protein expression (Western blot), and cellular compartmentalization were measured in isolated islets (collagenase digestion). FRD rats presented normoglycemia but impaired glucose tolerance, hypertriglyceridemia, hyperinsulinemia, and increased HOMA-IR index. In these rats, β-cell mass decreased significantly by 33%, with a 44% increase in the percentage of apoptotic cells. Glucose-induced insulin release and islet glucose metabolism were higher in FRD rats. While GK activity (total and cytosolic fraction) and protein expression were significantly higher in FRD islets, HK showed no change in any of these parameters. Our results demonstrate that the changes induced by dietary-induced IR upon β-cell function and mass are strongly conditional on the nutrient model used. In our model (intact animals with impaired glucose tolerance), GK activity increases through mechanisms previously shown only in vitro or under highly hyperglycemic conditions. Such an increase plays a pivotal role in the adaptive increased release of insulin in response to IR, even in the presence of marked β-cell mass reduction.Centro de Endocrinología Experimental y Aplicad

Mechanisms involved in the β-cell mass increase induced by chronic sucrose feeding to normal rats

The aim of the present study was to clarify the mechanisms by which a sucrose-rich diet (SRD) produces an increase in the pancreatic β-cell mass in the rat. Normal Wistar rats were fed for 30 weeks either an SRD (SRD rats; 63% wt/wt), or the same diet but with starch instead of sucrose in the same proportion (CD rats). We studied body weight, serum glucose and triacylglycerol levels, endocrine tissue and β-cell mass, β-cell replication rate (proliferating cell nuclear antigen; PCNA), islet neogenesis (cytokeratin immunostaining) and β-cell apoptosis (propidium iodide). Body weight (g) recorded in the SRD rats was significantly (P<0.05) larger than that of the CD group (556.0 ± 8.3 vs 470.0 ± 13.1). Both serum glucose and triacylglycerol levels (mmol/l) were also significantly higher (P<0.05) in SRD than in CD rats (serum glucose, 8.11 ± 0.14 vs 6.62 ± 0.17; triacyglycerol, 1.57 ± 0.18 vs 0.47 ± 0.04). The number of pancreatic islets per unit area increased significantly (P<0.05) in SRD rats (3.29 ± 0.1 vs 2.01 ± 0.2). A significant increment (2.6 times) in the mass of endocrine tissue was detected in SRD animals, mainly due to an increase in the β-cell mass (P=0.0025). The islet cell replication rate, measured as the percentage of PCNA-labelled β cells increased 6.8 times in SRD rats (P<0.03). The number of apoptotic cells in the endocrine pancreas decreased significantly (three times) in the SRD animals (P=0.03). The cytokeratin-positive area did not show significant differences between CD and SRD rats. The increase of β-cell mass induced by SRD was accomplished by an enhanced replication of β cells together with a decrease in the rate of β-cell apoptosis, without any evident participation of islet neogenesis. This pancreatic reaction was unable to maintain serum glucose levels of these rats at the level measured in CD animals.Centro de Endocrinología Experimental y AplicadaFacultad de Ciencias Médica

Migraine mediates the influence of C677T MTHFR genotypes on ischemic stroke risk with a stroke-subtype effect.

BACKGROUND AND PURPOSE: The objective was to investigate the role of C677T MTHFR polymorphism in migraine pathogenesis and in the migraine-ischemic stroke pathway. METHODS: A first genotype-migraine association study was conducted on 100 patients with migraine with aura (MA), 106 with migraine without aura (MO), and 105 subjects without migraine, which provided evidence in favor of association of the TT677 MTHFR genotype with increased risk of MA compared with both control subjects (OR, 2.48; 95% CI, 1.11 to 5.58) and patients with MO (OR, 2.21; 95% CI, 1.01 to 4.82). Based on these findings, mediational models of the genotype-migraine-stroke pathway were fitted on a group of 106 patients with spontaneous cervical artery dissection, 227 young patients whose ischemic stroke was unrelated to a spontaneous cervical artery dissection (noncervical artery dissection), and 187 control subjects, and a genotype-migraine partial mediation model was selected. RESULTS: Both migraine and the TT genotype were more strongly associated to the subgroup of patients with spontaneous cervical artery dissection (OR, 4.06; 95% CI, 1.63 to 10.02 for MA; OR, 5.45; 95% CI, 3.03 to 9.79 for MO; OR, 2.87; 95% CI, 1.45 to 5.68 for TT genotype) than to the subgroup of patients with noncervical artery dissection ischemic stroke (OR, 2.22; 95% CI, 1.00 to 4.96 for MA; OR, 1.81; 95% CI, 1.02 to 3.22 for TT genotype) as compared with controls. CONCLUSIONS: Migraine may act as mediator in the methylenetetrahydrofolate reductase-ischemic stroke pathway with a more prominent effect in the subgroup of patients with spontaneous artery dissection