Heat and mass transfer investigation of rotating hydrocarbons droplet which behaves as a hard sphere

AbstractThe steady state boundary layer equations around rotating pure hydrocarbon droplet are solved numerically. The droplet is simulated to behave as a hard sphere. The transfer equations are discretized using an implicit finite difference method where Thomas algorithm solves the system of algebraic equations. Moreover, dimensionless parameters of heat and mass transfer phenomena around a rotating hexane droplet concluded. The thickness of the boundary layer is unknown for this model and therefore, it is determined. Further, this work proposes correlations of Nusselt and Sherwood numbers for monocomponent hydrocarbon droplets in evaporation. These correlations consider the rotation phenomena and further, the variation of the thermophysical and transport properties in the vapour phase

Viscosity effects on liquid-liquid dispersion in laminar flows

Efficiency of liquid/liquid dispersion is an important stake in numerous sectors, such as the chemical, food, cosmetic and environmental industries. In the present study, dispersion is achieved in an open-loop reactor consisting of simple curved pipes, either helically coiled or chaotically twisted. In both configurations, we investigate the drop breakup process of two immiscible fluids (W/O) and especially the effect of the continuous phase viscosity, which is varied by addition of different fractions of butanol in the native sunflower oil. The global Reynolds numbers vary between 40 and 240, so that the flow remains laminar while the Dean roll-cells in the bends develop significantly. Different fractions of butanol are added to the oil in each case to examine the influence of the continuous phase viscosity on the drop size distribution of the dispersed phase (water). When the butanol fraction is decreased, the dispersion process is intensified and smaller drops are created. The Sauter mean diameters obtained in the chaotic twisted pipe are compared with those in a helically coiled pipe flow. The results show that chaotic advection intensifies the droplet breakup till 20% in droplet size reduction, and also reduces polydispersity

Structure-based design of allosteric calpain-1 inhibitors populating a novel bioactivity space.

Dimeric calpains constitute a promising therapeutic target for many diseases such as cardiovascular, neurodegenerative and ischaemic disease. The discovery of selective calpain inhibitors, however, has been extremely challenging. Previously, allosteric inhibitors of calpains, such as PD150606, which included a specific α-mercaptoacrylic acid sub-structure, were reported to bind to the penta-EF hand calcium binding domain, PEF(S) of calpain. Although these are selective to calpains over other cysteine proteases, their mode of action has remained elusive due to their ability to inhibit the active site domain with and without the presence of PEF(S), with similar potency. These findings have led to the question of whether the inhibitory response can be attributed to an allosteric mode of action or alternatively to inhibition at the active site. In order to address this problem, we report a structure-based virtual screening protocol as a novel approach for the discovery of PEF(S) binders that populate a novel chemical space. We have identified compound 1, Vidupiprant, which is shown to bind to the PEF(S) domain by the TNS displacement method, and it exhibited specificity in its allosteric mode of inhibition. Compound 1 inhibited the full-length calpain-1 complex with a higher potency (IC50 = 7.5 μM) than the selective, cell-permeable non-peptide calpain inhibitor, PD150606 (IC50 = 19.3 μM), where the latter also inhibited the active site domain in the absence of PEF(S) (IC50 = 17.8 μM). Hence the method presented here has identified known compounds with a novel allosteric mechanism for the inhibition of calpain-1. We show for the first time that the inhibition of enzyme activity can be attributed to an allosteric mode of action, which may offer improved selectivity and a reduced side-effects profile

Microvascular vasodilator properties of the angiotensin II type 2 receptor in a mouse model of type 1 diabetes

Diabetes Mellitus is associated with severe cardiovascular disorders involving the renin-angiotensin system, mainly through activation of the angiotensin II type 1 receptor (AT1R). Although the type 2 receptor (AT2R) opposes the effects of AT1R, with vasodilator and anti-trophic properties, its role in diabetes is debatable. Thus we investigated AT2R-mediated dilatation in a model of type 1 diabetes induced by streptozotocin in 5-month-old male mice lacking AT2R (AT2R). Glucose tolerance was reduced and markers of inflammation and oxidative stress (cyclooxygenase-2, gp91phox p22phox and p67phox) were increased in AT2R mice compared to wild-type (WT) animals. Streptozotocin-induced hyperglycaemia was higher in AT2R than in WT mice. Arterial gp91phox and MnSOD expression levels in addition to blood 8-isoprostane and creatinine were further increased in diabetic AT2R mice compared to diabetic WT mice. AT2R-dependent dilatation in both isolated mesenteric resistance arteries and perfused kidneys was greater in diabetic mice than in non-diabetic animals. Thus, in type 1 diabetes, AT2R may reduce glycaemia and display anti-oxidant and/or anti-inflammatory properties in association with greater vasodilatation in mesenteric arteries and in the renal vasculature, a major target of diabetes. Therefore AT2R might represent a new therapeutic target in diabetes

The effect of reverse current on the dark properties of photovoltaic solar modules

AbstractForward and reverse dark current-voltage (I-V) and capacitance-voltage (C-V) characteristics of commercial amorphous silicon solar modules, were measured in order to study their performance under the influence of induced reverse currents. Maximum module surface temperatures were directly related to each value of the induced reverse current and in to the amount of current leakage respectively. Microscopic changes as a result of hot spots defects and overheating of the solar module, linked to reverse current effects, were also documented and discussed. Experimental evidence showed that different levels of reverse currents are confirmed to be a major degrading factor affecting the performance, efficiency, and power of solar modules

Infrared nanospectroscopy reveals the molecular interaction fingerprint of an aggregation inhibitor with single Aβ42 oligomers

Abstract: Significant efforts have been devoted in the last twenty years to developing compounds that can interfere with the aggregation pathways of proteins related to misfolding disorders, including Alzheimer’s and Parkinson’s diseases. However, no disease-modifying drug has become available for clinical use to date for these conditions. One of the main reasons for this failure is the incomplete knowledge of the molecular mechanisms underlying the process by which small molecules interact with protein aggregates and interfere with their aggregation pathways. Here, we leverage the single molecule morphological and chemical sensitivity of infrared nanospectroscopy to provide the first direct measurement of the structure and interaction between single Aβ42 oligomeric and fibrillar species and an aggregation inhibitor, bexarotene, which is able to prevent Aβ42 aggregation in vitro and reverses its neurotoxicity in cell and animal models of Alzheimer’s disease. Our results demonstrate that the carboxyl group of this compound interacts with Aβ42 aggregates through a single hydrogen bond. These results establish infrared nanospectroscopy as a powerful tool in structure-based drug discovery for protein misfolding diseases

Rational design of a conformation-specific antibody for the quantification of A beta oligomers

The accurate quantification of the amounts of small oligomeric assemblies formed by the amyloid β (Aβ) peptide represents a major challenge in the Alzheimer’s field. There is therefore great interest in the development of methods to specifically detect these oligomers by distinguishing them from larger aggregates. The availability of these methods will enable the development of effective diagnostic and therapeutic interventions for this and other diseases related to protein misfolding and aggregation. We describe here a single-domain antibody able to selectively quantify oligomers of the Aβ peptide in isolation and in complex protein mixtures from animal models of disease

Influence of biofuels on the internal flow in diesel injector nozzles

[EN] In this paper, the behavior of the internal nozzle flow of a standard diesel fuel has been compared against a biodiesel fuel (soybean oil) at cavitating and non-cavitating conditions, using a homogeneous equilibrium model. The model takes into account the compressibility of both phases (liquid and vapour) and use a barotropic equation of state which relates pressure and density to calculate the growth of cavitation. Furthermore, turbulence effects have been introduced using a RNG k- ¿ model.The comparison of both fuels in a real diesel injector nozzle has been performed in terms of mass flow, momentum flux, effective velocity at the outlet and cavitation appearance. The decrease of injection velocity and cavitation intensity for the biodiesel noticed by numerical simulation at different injection conditions, predict a worse air-fuel mixing process.This work was partly sponsored by "Generalitat Valenciana" in the framework of the project "Estudio del flujo en el interior de toberas de inyeccion diesel", Reference GV/2009/031. The authors would also like to express gratitude for the computer resources, technical expertise and assistance provided by the Universidad de Valencia relating to the use of the supercomputer "Tirant".Salvador, F.; Martínez López, J.; Romero Bauset, JV.; Roselló, M. (2011). Influence of biofuels on the internal flow in diesel injector nozzles. Mathematical and Computer Modelling. 54(7):1699-1705. https://doi.org/10.1016/j.mcm.2010.12.010S1699170554

Trodusquemine displaces protein misfolded oligomers from cell membranes and abrogates their cytotoxicity through a generic mechanism

The onset and progression of numerous protein misfolding diseases are associated with the presence of oligomers formed during the aberrant aggregation of several different proteins, including amyloid-ß (Aß) in Alzheimer’s disease and a-synuclein (aS) in Parkinson’s disease. These small, soluble aggregates are currently major targets for drug discovery. In this study, we show that trodusquemine, a naturally-occurring aminosterol, markedly reduces the cytotoxicity of aS, Aß and HypF-N oligomers to human neuroblastoma cells by displacing the oligomers from cell membranes in the absence of any substantial morphological and structural changes to the oligomers. These results indicate that the reduced toxicity results from a mechanism that is common to oligomers from different proteins, shed light on the origin of the toxicity of the most deleterious species associated with protein aggregation and suggest that aminosterols have the therapeutically-relevant potential to protect cells from the oligomer-induced cytotoxicity associated with numerous protein misfolding diseases