Cavitation Effects on Squeeze-Film Damper Performance

Nan, Feng; Hahn, E. J.

doi:10.1080/05698198608981696

Cited by 29 publications

(30 citation statements)

References 8 publications

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“…Because isolation of guinea pig ventricular (GPV) cells is well established in the laboratory and cells were readily available from other studies, guinea pig cardiomyocytes were used for electrophysiology experiments. As Ca v 1.2 channels carry the L-type Ca 2+ current (I Ca,L ) in guinea pig (Feng et al, 2014;Nassal et al, 2016) as well as rat ventricular myocytes (Schwoerer et al, 2013;Liu et al, 2014b), it is reasonable to assume that 5-HMF affects this current in a similar way in both species. To exclude the possibility that effects observed in guinea pig cells were absent in rat ventricular myocytes, key experiments were repeated with rat isolated cardiomyocytes confirming the results with cells isolated from guinea pigs (not shown).…”

Section: Validity Of Animal Species and Model Selectionmentioning

confidence: 99%

Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca²⁺ currents

Wölkart

Schrammel

Koyani

et al. 2017

British J Pharmacology

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Background and PurposeThe antioxidant 5‐hydroxymethylfurfural (5‐HMF) exerts documented beneficial effects in several experimental pathologies and is currently tested as an antisickling drug in clinical trials. In the present study, we examined the cardiovascular effects of 5‐HMF and elucidated the mode of action of the drug.Experimental ApproachThe cardiovascular effects of 5‐HMF were studied with pre‐contracted porcine coronary arteries and rat isolated normoxic‐perfused hearts. Isolated hearts subjected to ischaemia/reperfusion (I/R) injury were used to test for potential cardioprotective effects of the drug. The effects of 5‐HMF on action potential and L‐type Ca2+ current (ICa,L) were studied by patch‐clamping guinea pig isolated ventricular cardiomyocytes.Key Results5‐HMF relaxed coronary arteries in a concentration‐dependent manner and exerted negative inotropic, lusitropic and chronotropic effects in rat isolated perfused hearts. On the other hand, 5‐HMF improved recovery of inotropic and lusitropic parameters in isolated hearts subjected to I/R. Patch clamp experiments revealed that 5‐HMF inhibits L‐type Ca2+ channels. Reduced ICa,L density, shift of ICa,L steady‐state inactivation curves toward negative membrane potentials and slower recovery of ICa,L from inactivation in response to 5‐HMF accounted for the observed cardiovascular effects.Conclusions and ImplicationsOur data revealed a cardioprotective effect of 5‐HMF in I/R that is mediated by inhibition of L‐type Ca2+ channels. Thus, 5‐HMF is suggested as a beneficial additive to cardioplegic solutions, but adverse effects and contraindications of Ca2+ channel blockers have to be considered in therapeutic application of the drug.

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Section: Validity Of Animal Species and Model Selectionmentioning

confidence: 99%

Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca²⁺ currents

Wölkart

Schrammel

Koyani

et al. 2017

British J Pharmacology

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“…(iv) The effect of the motion of a single scatterer has not been addressed in directed path theories. Broad distributions of the log-conductance with a quasi-universal variance have been numerically observed without a directed path approximation [12].…”

Section: Introductionmentioning

confidence: 99%

Quantum transmission in disordered insulators: random matrix theory and transverse localization

Avishai¹,

Pichaxd²,

Muttalib³

1993

J. Phys. I France

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We consider quantum interferences of classically allowed or forbidden electronic trajectories in disordered dielectrics. Without assuming a directed path approximation, we represent a strongly disordered elastic scatterer by its transmission matrix t. We recall how the eigenvalue distribution of t.t † can be obtained from a certain ansatz leading to a Coulomb gas analogy at a temperature β −1 which depends on the system symmetries. We recall the consequences of this random matrix theory for quasi-1d insulators and we extend our study to microscopic three dimensional models in the presence of transverse localization. For cubes of size L, we find two regimes for the spectra of t.t † as a function of the localization length ξ. For L/ξ ≈ 1 − 5, the eigenvalue spacing distribution remains close to the Wigner surmise (eigenvalue repulsion). The usual orthogonal-unitary crossover is observed for large magnetic field change ∆B ≈ Φ 0 /ξ 2 where Φ 0 denotes the flux quantum. This field reduces the conductance fluctuations and the average log-conductance (increase of ξ) and induces on a given sample large magneto-conductance fluctuations of typical magnitude similar to the sample to sample fluctuations (ergodic behaviour). When ξ is of the order of the lattice spacing (L/ξ ≫ 5 − 6), the eigenvalue repulsion is weaker and the removal of a time reversal symmetry has a more negligible role. In those two regimes, the sample to sample fluctuations of the log-conductance are close to a normal one-parameter distribution, and ξ −1 depends linearly on the disorder parameter. In these microscopic models, the Fermi energy dependence of the conductance is very similar to the one recently observed in small GaAs:Si wires. Résumé:Nous considérons les interférences quantiques de trajectoires electroniques classiquement permises ou interdites dans des diélectriques désordonnés. Sans faire une approximation de chemins dirigés, nous représentons un diffuseurélastique très désordonné par sa matrice de transmission t. Nous rappelons comment la distribution des valeurs propres de t.t † peutêtre obtenueà partir d'un certain ansatz conduisantà une analogie avec un gaz de Coulombà une temperature β −1 qui depend des symètries du système. Nous rappelons les conséquences de cette theorie de matrices aleatoires pour des isolants quasi-1d et nousétendons notreétudeà des modèles microscopiques tridimensionnels où la localisation transverse est présente. Pour des cubes de taille L, suivant la valeur de la longueur de localisation ξ, nous trouvons deux regimes pour les spectres de t.t † . Quand L/ξ ≈ 1−5, la distibution des espacements entre valeurs propres reste proche de celle de Wigner (repulsion des valeurs propres). Le cross-over habituel entre les cas orthogonal et unitaire a lieu pour un champ magnetique appliquéélevé ∆B ≈ Φ o /ξ 2 où Φ o est le quantum de flux. Ce même champ réduit les fluctuations de conductance g ainsi que la moyenne de log(g) (augmentation de ξ) et induit sur un echantillon donné de grandes fluctuations de la magnetoconductance...

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“…In this research, the cavitation pressure cav p is set to -101.325 kPa (absolute zero) as recommended in [13,18] and used in [1][2][3].…”

Section: Sfd Modelsmentioning

confidence: 99%

An Investigation Into Two Alternative Approaches for the Identification of SFD Bearings for Aeroengine Analysis

Groves

Bonello

2011

Volume 6: Structures and Dynamics, Parts a and B

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Identification techniques provide a means of efficiently implementing complex nonlinear bearing models in practical turbomachinery applications. This paper considers both identification from an advanced numerical model and identification from experimental tests. Identification from numerical models is essential at the design stage, where rapid simulation of the dynamic performance of a variety of designs is required. Experimental identification is useful to capture effects that are difficult to model (e.g. geometric imperfections, compressibility and its effect on cavitation). With regard to identification from a numerical model, it was shown in a previous paper that the numerical solution of the incompressible Reynolds equation may be replicated using Chebyshev polynomial fits. Tests were performed on a simple rotor-bearing configuration incorporating an advanced numerical bearing model. The identified model was found to be able to match the accuracy of the numerical solution to the Reynolds equation while requiring a fraction of the computation time. In the present work the SFD identification scheme is applied to a realistically-sized representative wholeaeroengine model. It is shown that using recently introduced nonlinear solvers combined with the identified high accuracy bearing models it is possible to run full engine rotor-dynamic simulations, in both the time and frequency domains, at a fraction of the previous computational cost. One major drawback of the Chebyshev technique is that it is not amenable to experimental identification of actual bearings. For this reason, a second identification approach, involving the use of neural networks, is considered in this paper. A test rig that enables empirical identification of SFD forces has been constructed and details of the building and operation of the test rig is presented. The method used to ascertain the training data required by the neural network identification scheme, is also described. Downloaded From: http://proceedings.asmedigitalcollection.asme.org/ on 03/30/2015 Terms of Use: http://asme.org/terms y J J J J J y

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Cavitation Effects on Squeeze-Film Damper Performance

Cited by 29 publications

References 8 publications

Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca²⁺ currents

Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca²⁺ currents

Quantum transmission in disordered insulators: random matrix theory and transverse localization

An Investigation Into Two Alternative Approaches for the Identification of SFD Bearings for Aeroengine Analysis

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Cavitation Effects on Squeeze-Film Damper Performance

Cited by 29 publications

References 8 publications

Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca2+ currents

Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca2+ currents

Quantum transmission in disordered insulators: random matrix theory and transverse localization

An Investigation Into Two Alternative Approaches for the Identification of SFD Bearings for Aeroengine Analysis

Contact Info

Product

Resources

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Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca²⁺ currents

Cardioprotective effects of 5‐hydroxymethylfurfural mediated by inhibition of L‐type Ca²⁺ currents