Pro-oxidant effect of α-tocopherol in patients with Type 2 Diabetes after an oral glucose tolerance test – a randomised controlled trial

BACKGROUND: As a part of a larger study investigating the effects of α-tocopherol on gene expression in type 2 diabetics we observed a pro-oxidant effect of α-tocopherol which we believe may be useful in interpreting outcomes of large intervention trials of α-tocopherol. METHODS: 19 type 2 diabetes subjects were randomised into two groups taking either 1200 IU/day of α-tocopherol or a matched placebo for 4 weeks. On day 0 and 29 of this study oxidative DNA damage was assessed in mononuclear cells from fasted blood samples and following a 2 h glucose tolerance test (GTT). RESULTS: On day 0 there was no significant difference in oxidative DNA damage between the two groups or following a GTT. On day 29 there was no significant difference in oxidative DNA damage in fasted blood samples, however following a GTT there was a significant increase in oxidative DNA damage in the α-tocopherol treatment group. CONCLUSION: High dose supplementation with α-tocopherol primes mononuclear cells from patients with type 2 diabetes for a potentially damaging response to acute hyperglycaemia

Experimental validation of a one-dimensional twin-entry radial turbine model under non-linear pulse conditions

This is the author¿s version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419869157[EN] This article presents the experimental validation of a complete integrated one-dimensional twin-scroll turbine model able to be used in reciprocating internal combustion engine unsteady simulations. A passenger car with a twin-entry-type turbine has been tested under engine-like pulse conditions by means of a specifically built gas stand. To obtain high-resolution quality data, the turbine and turbine line pipes have been instrumented with mean and instantaneous pressure sensors as well as temperature and mass flow sensors, employing a uniquely designed rotating valve for the pulse generation. This experimental configuration enables to obtain the pressure decomposition in both inlets and outlets of the turbine. Using the experimental data obtained, the model is fully validated, with special focus on the reflected and transmitted components for analysing the performance of the model and its non-linear acoustics prediction capabilities. The model presents a very high degree of correlation with the experimental results, providing a range of errors similar to the uncertainty of the measurements, even in the medium- and high-frequency spectra.The author(s) disclosed receipt of the following financial support for the research, authorship and/or publication of this article: This work was supported by the 'Ayuda a Primeros Proyectos de Investigacion' (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia (UPV), Valencia, Spain. P.S. was partially supported through contract FPI-2017-S2-1428 of Programa de Apoyo para la Investigacion y Desarrollo (PAID) of Universitat Politecnica de Valencia.Serrano, J.; Arnau Martínez, FJ.; García-Cuevas González, LM.; Soler-Blanco, P.; Cheung, R. (2021). Experimental validation of a one-dimensional twin-entry radial turbine model under non-linear pulse conditions. International Journal of Engine Research. 22(2):390-406. https://doi.org/10.1177/1468087419869157S390406222Watson, N., & Janota, M. S. (1982). Turbocharging the Internal Combustion Engine. doi:10.1007/978-1-349-04024-7Galindo, J., Fajardo, P., Navarro, R., & García-Cuevas, L. M. (2013). Characterization of a radial turbocharger turbine in pulsating flow by means of CFD and its application to engine modeling. Applied Energy, 103, 116-127. doi:10.1016/j.apenergy.2012.09.013Torregrosa, A. J., Broatch, A., Navarro, R., & García-Tíscar, J. (2014). Acoustic characterization of automotive turbocompressors. International Journal of Engine Research, 16(1), 31-37. doi:10.1177/1468087414562866Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Piscaglia, F., Onorati, A., Marelli, S., & Capobianco, M. (2018). A detailed one-dimensional model to predict the unsteady behavior of turbocharger turbines for internal combustion engine applications. International Journal of Engine Research, 20(3), 327-349. doi:10.1177/1468087417752525Galindo, J., Arnau, F. J., García-Cuevas, L. M., & Soler, P. (2018). Experimental validation of a quasi-two-dimensional radial turbine model. International Journal of Engine Research, 21(6), 915-926. doi:10.1177/1468087418788502Rajoo, S., Romagnoli, A., & Martinez-Botas, R. F. (2012). Unsteady performance analysis of a twin-entry variable geometry turbocharger turbine. Energy, 38(1), 176-189. doi:10.1016/j.energy.2011.12.017Rajoo, S., & Martinez-Botas, R. (2008). Variable Geometry Mixed Flow Turbine for Turbochargers: An Experimental Study. International Journal of Fluid Machinery and Systems, 1(1), 155-168. doi:10.5293/ijfms.2008.1.1.155Copeland, C. D., Martinez-Botas, R., & Seiler, M. (2010). Comparison Between Steady and Unsteady Double-Entry Turbine Performance Using the Quasi-Steady Assumption. Journal of Turbomachinery, 133(3). doi:10.1115/1.4000580Copeland, C. D., Martinez-Botas, R., & Seiler, M. (2011). Unsteady Performance of a Double Entry Turbocharger Turbine With a Comparison to Steady Flow Conditions. Journal of Turbomachinery, 134(2). doi:10.1115/1.4003171Costall, A. W., McDavid, R. M., Martinez-Botas, R. F., & Baines, N. C. (2010). Pulse Performance Modeling of a Twin Entry Turbocharger Turbine Under Full and Unequal Admission. Journal of Turbomachinery, 133(2). doi:10.1115/1.4000566Yang, M., Martinez-Botas, R., Rajoo, S., Yokoyama, T., & Ibaraki, S. (2015). An investigation of volute cross-sectional shape on turbocharger turbine under pulsating conditions in internal combustion engine. Energy Conversion and Management, 105, 167-177. doi:10.1016/j.enconman.2015.06.038Copeland, C. D., Newton, P. J., Martinez-Botas, R., & Seiler, M. (2011). The Effect of Unequal Admission on the Performance and Loss Generation in a Double-Entry Turbocharger Turbine. Journal of Turbomachinery, 134(2). doi:10.1115/1.4003226Cerdoun, M., & Ghenaiet, A. (2018). Unsteady behaviour of a twin entry radial turbine under engine like inlet flow conditions. Applied Thermal Engineering, 130, 93-111. doi:10.1016/j.applthermaleng.2017.11.001Payri, F., Benajes, J., & Reyes, M. (1996). Modelling of supercharger turbines in internal-combustion engines. International Journal of Mechanical Sciences, 38(8-9), 853-869. doi:10.1016/0020-7403(95)00105-0Chiong, M. S., Rajoo, S., Martinez-Botas, R. F., & Costall, A. W. (2012). Engine turbocharger performance prediction: One-dimensional modeling of a twin entry turbine. Energy Conversion and Management, 57, 68-78. doi:10.1016/j.enconman.2011.12.001Chiong, M. S., Rajoo, S., Romagnoli, A., Costall, A. W., & Martinez-Botas, R. F. (2016). One-dimensional pulse-flow modeling of a twin-scroll turbine. Energy, 115, 1291-1304. doi:10.1016/j.energy.2016.09.041Galindo, J., Navarro, R., García-Cuevas, L. M., Tarí, D., Tartoussi, H., & Guilain, S. (2018). A zonal approach for estimating pressure ratio at compressor extreme off-design conditions. International Journal of Engine Research, 20(4), 393-404. doi:10.1177/1468087418754899Payri, F., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). External heat losses in small turbochargers: Model and experiments. Energy, 71, 534-546. doi:10.1016/j.energy.2014.04.096Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2015). Turbocharger heat transfer and mechanical losses influence in predicting engines performance by using one-dimensional simulation codes. Energy, 86, 204-218. doi:10.1016/j.energy.2015.03.130Gil, A., Tiseira, A. O., García-Cuevas, L. M., Usaquén, T. R., & Mijotte, G. (2018). Fast three-dimensional heat transfer model for computing internal temperatures in the bearing housing of automotive turbochargers. International Journal of Engine Research, 21(8), 1286-1297. doi:10.1177/1468087418804949Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042Piñero, G., Vergara, L., Desantes, J. M., & Broatch, A. (2000). Estimation of velocity fluctuation in internal combustion engine exhaust systems through beamforming techniques. Measurement Science and Technology, 11(11), 1585-1595. doi:10.1088/0957-0233/11/11/307Zimmermann, R., Baar, R., & Biet, C. (2016). Determination of the isentropic turbine efficiency due to adiabatic measurements and the validation of the conditions via a new criterion. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 232(24), 4485-4494. doi:10.1177/0954406216670683Serrano, J. R., Arnau, F. J., Gracía-Cuevas, L. M., Samala, V., & Smith, L. (2019). Experimental approach for the characterization and performance analysis of twin entry radial-inflow turbines in a gas stand and with different flow admission conditions. Applied Thermal Engineering, 159, 113737. doi:10.1016/j.applthermaleng.2019.113737Serrano, J. R., Olmeda, P., Páez, A., & Vidal, F. (2010). An experimental procedure to determine heat transfer properties of turbochargers. Measurement Science and Technology, 21(3), 035109. doi:10.1088/0957-0233/21/3/035109Serrano, J. R., Arnau, F. J., Dolz, V., Tiseira, A., & Cervelló, C. (2008). A model of turbocharger radial turbines appropriate to be used in zero- and one-dimensional gas dynamics codes for internal combustion engines modelling. Energy Conversion and Management, 49(12), 3729-3745. doi:10.1016/j.enconman.2008.06.031Serrano, J. R., Arnau, F. J., Fajardo, P., Reyes Belmonte, M. A., & Vidal, F. (2012). Contribution to the Modeling and Understanding of Cold Pulsating Flow Influence in the Efficiency of Small Radial Turbines for Turbochargers. Journal of Engineering for Gas Turbines and Power, 134(10). doi:10.1115/1.4007027Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., Dombrovsky, A., & Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Conversion and Management, 128, 281-293. doi:10.1016/j.enconman.2016.09.032Chen, H., Hakeem, I., & Martinez-Botas, R. F. (1996). Modelling of a Turbocharger Turbine Under Pulsating Inlet Conditions. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 210(5), 397-408. doi:10.1243/pime_proc_1996_210_063_02Galindo, J., Serrano, J. R., Arnau, F. J., & Piqueras, P. (2009). Description of a Semi-Independent Time Discretization Methodology for a One-Dimensional Gas Dynamics Model. Journal of Engineering for Gas Turbines and Power, 131(3). doi:10.1115/1.2983015Van Leer, B. (1974). Towards the ultimate conservative difference scheme. II. Monotonicity and conservation combined in a second-order scheme. Journal of Computational Physics, 14(4), 361-370. doi:10.1016/0021-9991(74)90019-9Toro, E. F., Spruce, M., & Speares, W. (1994). Restoration of the contact surface in the HLL-Riemann solver. Shock Waves, 4(1), 25-34. doi:10.1007/bf01414629Courant, R., Friedrichs, K., & Lewy, H. (1928). �ber die partiellen Differenzengleichungen der mathematischen Physik. Mathematische Annalen, 100(1), 32-74. doi:10.1007/bf01448839Harris, F. J. (1978). On the use of windows for harmonic analysis with the discrete Fourier transform. Proceedings of the IEEE, 66(1), 51-83. doi:10.1109/proc.1978.10837Welch, P. (1967). The use of fast Fourier transform for the estimation of power spectra: A method based on time averaging over short, modified periodograms. IEEE Transactions on Audio and Electroacoustics, 15(2), 70-73. doi:10.1109/tau.1967.116190

Analysis of the influence of different real flow effects on computational fluid dynamics boundary conditions based on the method of characteristics

Nowadays, turbocharged internal combustion engines (ICEs) are very common in automotive powerplants, monopolizing the Diesel sector and having a steadily increasing percentage in the gasoline one. In this frame, the interest in modeling the behavior of the turbomachinery components involved, with the ultimate goal of characterizing the performance of the turbocharged ICE, seems clear. A turbomachine can be simulated using 3D-CFD software, but its computational cost does not allow to reproduce the whole turbocharger test rig. Moreover, the existence of long ducts requires a considerable computational time until the pressure reflections at the boundaries dissipate in order to reach a periodic solution. The use of non-reflecting boundary conditions reduces the needed length of ducts without introducing spurious wave reflections. An anechoic boundary condition (BC) based on the Method of Characteristics has been previously developed, considering the case of an inviscid and adiabatic 1D flow of a perfect gas. However, real flows do not behave in such ideal manner. In this paper, the extension of the scope of the previous BC is sought. In this way, a methodology to evaluate the performance of the anechoic BC under these real flow situations is shown. The consideration of ideal gas instead of perfect gas, the flow viscosity and the non-homentropic flow makes it necessary to modify the Method of Characteristics, since the Riemann Invariants are not constant any more. In this frame they are referred to as Riemann Variables. An additional issue that has been considered is the effect of swirl flow, as the one in the turbine outlet, on the anechoic BC. Some improvements to be implemented in the BC are proposed in order to have a better performance in these real flow situations.Galindo, J.; Tiseira Izaguirre, AO.; Fajardo, P.; Navarro García, R. (2013). Analysis of the influence of different real flow effects on computational fluid dynamics boundary conditions based on the method of characteristics. Mathematical and Computer Modelling. 57(7-8):1957-1964. doi:10.1016/j.mcm.2012.01.016S19571964577-

Application of the two-step Lax and Wendroff FCT and the CE-SE method to flow transport in wall-flow monoliths

[EN] Gas dynamic codes are computational tools applied to the analysis of air management in internal combustion engines. The governing equations in one-dimensional elements are approached assuming compressible unsteady non-homentropic flow and are commonly solved applying finite difference numerical methods. These techniques can also be applied to the calculation of flow transport in complex systems such as wallflow monoliths. These elements are characterized by alternatively plugged channels with porous walls. It filters the particulates when the flowgoes through thewall from the inlet to the outlet channels. Therefore, this process couples the solution of every pair of inlet and outlet channels. In this study, the adaptation of the two-step Lax and Wendroff method and the space-time Conservation Element and Solution Element method is performed to be applied in the solution of flow transport in wall-flow monolith channels. The influence on the prediction ability is analysed by a shock-tube test and experimental data obtained under impulsive flow conditions.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion through grant number DPI2010-20891-C02-02.Serrano, JR.; Arnau Martínez, FJ.; Piqueras, P.; García Afonso, Ó. (2014). Application of the two-step Lax and Wendroff FCT and the CE-SE method to flow transport in wall-flow monoliths. International Journal of Computer Mathematics. 91(1):71-84. https://doi.org/10.1080/00207160.2013.783206S718491

Radial turbine sound and noise characterisation with acoustic transfer matrices by means of fast one-dimensional models

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419889429.[EN] Estimating correctly the turbine acoustics can be valuable during the engine design stage; in fact, it can lead to a more optimised design of the silencer and aftertreatment, as well as to better prediction of the scavenging effects. However, obtaining the sound and noise emissions of radial turbocharger turbines with low computational costs can be challenging. To consider these effects in a time-efficient manner, the acoustic response of single-entry radial turbines can be characterised by means of acoustic transfer matrices that change with the operating conditions. Exploiting the different time-scales of the acoustic phenomena and the change in the operating point of the turbine, lookup tables of acoustic transfer matrices can be computed. Then, the obtained characterisation can be used in mean-value engine models. This article presents a method for generating these lookup tables by means of fast one-dimensional simulations of thoroughly validated fidelity, in terms of both acoustics and extrapolation capabilities. Due to the inherent behaviour of radial turbines, the number of computations needed to fill the lookup tables is relatively small, so the method can be used as a simple preprocessing phase before mean-value simulation campaigns.Torregrosa, AJ.; García-Cuevas González, LM.; Inhestern, LB.; Soler-Blanco, P. (2021). Radial turbine sound and noise characterisation with acoustic transfer matrices by means of fast one-dimensional models. International Journal of Engine Research. 22(4):1312-1328. https://doi.org/10.1177/1468087419889429S13121328224Broatch, A., Galindo, J., Navarro, R., & García-Tíscar, J. (2014). Methodology for experimental validation of a CFD model for predicting noise generation in centrifugal compressors. International Journal of Heat and Fluid Flow, 50, 134-144. doi:10.1016/j.ijheatfluidflow.2014.06.006Galindo, J., Tiseira, A., Navarro, R., Tarí, D., & Meano, C. M. (2017). Effect of the inlet geometry on performance, surge margin and noise emission of an automotive turbocharger compressor. Applied Thermal Engineering, 110, 875-882. doi:10.1016/j.applthermaleng.2016.08.099Peat, K. S., Torregrosa, A. J., Broatch, A., & Fernández, T. (2006). An investigation into the passive acoustic effect of the turbine in an automotive turbocharger. Journal of Sound and Vibration, 295(1-2), 60-75. doi:10.1016/j.jsv.2005.11.033Torregrosa, A., Galindo, J., Serrano, J. R., & Tiseira, A. (2009). A Procedure for the Unsteady Characterization of Turbochargers in Reciprocating Internal Combustion Engines. Fluid Machinery and Fluid Mechanics, 72-79. doi:10.1007/978-3-540-89749-1_10Torregrosa, A. J., Broatch, A., Navarro, R., & García-Tíscar, J. (2014). Acoustic characterization of automotive turbocompressors. International Journal of Engine Research, 16(1), 31-37. doi:10.1177/1468087414562866Broatch, A., Galindo, J., Navarro, R., García-Tíscar, J., Daglish, A., & Sharma, R. K. (2015). Simulations and measurements of automotive turbocharger compressor whoosh noise. Engineering Applications of Computational Fluid Mechanics, 9(1), 12-20. doi:10.1080/19942060.2015.1004788Broatch, A., Galindo, J., Navarro, R., & García-Tíscar, J. (2016). Numerical and experimental analysis of automotive turbocharger compressor aeroacoustics at different operating conditions. International Journal of Heat and Fluid Flow, 61, 245-255. doi:10.1016/j.ijheatfluidflow.2016.04.003Wallace, F. J., & Adgey, J. (1967). Paper 1: Theoretical Assessment of the Non-Steady Flow Performance of Inward Radial Flow Turbines. Proceedings of the Institution of Mechanical Engineers, Conference Proceedings, 182(8), 22-36. doi:10.1243/pime_conf_1967_182_211_02Piscaglia, F., Onorati, A., Marelli, S., & Capobianco, M. (2018). A detailed one-dimensional model to predict the unsteady behavior of turbocharger turbines for internal combustion engine applications. International Journal of Engine Research, 20(3), 327-349. doi:10.1177/1468087417752525Galindo, J., Fajardo, P., Navarro, R., & García-Cuevas, L. M. (2013). Characterization of a radial turbocharger turbine in pulsating flow by means of CFD and its application to engine modeling. Applied Energy, 103, 116-127. doi:10.1016/j.apenergy.2012.09.013Galindo, J., Tiseira, A., Fajardo, P., & García-Cuevas, L. M. (2014). Development and validation of a radial variable geometry turbine model for transient pulsating flow applications. Energy Conversion and Management, 85, 190-203. doi:10.1016/j.enconman.2014.05.072Avola, C., Copeland, C., Romagnoli, A., Burke, R., & Dimitriou, P. (2017). Attempt to correlate simulations and measurements of turbine performance under pulsating flows for automotive turbochargers. Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, 233(2), 174-187. doi:10.1177/0954407017739123Galindo, J., Climent, H., Tiseira, A., & García-Cuevas, L. M. (2016). Effect of the numerical scheme resolution on quasi-2D simulation of an automotive radial turbine under highly pulsating flow. Journal of Computational and Applied Mathematics, 291, 112-126. doi:10.1016/j.cam.2015.02.025Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., Dombrovsky, A., & Tartoussi, H. (2016). Development and validation of a radial turbine efficiency and mass flow model at design and off-design conditions. Energy Conversion and Management, 128, 281-293. doi:10.1016/j.enconman.2016.09.032Galindo, J., Navarro, R., García-Cuevas, L. M., Tarí, D., Tartoussi, H., & Guilain, S. (2018). A zonal approach for estimating pressure ratio at compressor extreme off-design conditions. International Journal of Engine Research, 20(4), 393-404. doi:10.1177/1468087418754899Payri, F., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). External heat losses in small turbochargers: Model and experiments. Energy, 71, 534-546. doi:10.1016/j.energy.2014.04.096Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2015). Turbocharger heat transfer and mechanical losses influence in predicting engines performance by using one-dimensional simulation codes. Energy, 86, 204-218. doi:10.1016/j.energy.2015.03.130Serrano, J. R., Olmeda, P., Tiseira, A., García-Cuevas, L. M., & Lefebvre, A. (2013). Theoretical and experimental study of mechanical losses in automotive turbochargers. Energy, 55, 888-898. doi:10.1016/j.energy.2013.04.042Piñero, G., Vergara, L., Desantes, J. M., & Broatch, A. (2000). Estimation of velocity fluctuation in internal combustion engine exhaust systems through beamforming techniques. Measurement Science and Technology, 11(11), 1585-1595. doi:10.1088/0957-0233/11/11/307Galindo, J., Serrano, J. R., Arnau, F. J., & Piqueras, P. (2009). Description of a Semi-Independent Time Discretization Methodology for a One-Dimensional Gas Dynamics Model. Journal of Engineering for Gas Turbines and Power, 131(3). doi:10.1115/1.2983015Serrano, J. R., Arnau, F. J., Dolz, V., Tiseira, A., & Cervelló, C. (2008). A model of turbocharger radial turbines appropriate to be used in zero- and one-dimensional gas dynamics codes for internal combustion engines modelling. Energy Conversion and Management, 49(12), 3729-3745. doi:10.1016/j.enconman.2008.06.031Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Welch, P. (1967). The use of fast Fourier transform for the estimation of power spectra: A method based on time averaging over short, modified periodograms. IEEE Transactions on Audio and Electroacoustics, 15(2), 70-73. doi:10.1109/tau.1967.1161901Serrano, J. R., Arnau, F. J., García-Cuevas, L. M., & Inhestern, L. B. (2019). An innovative losses model for efficiency map fitting of vaneless and variable vaned radial turbines extrapolating towards extreme off-design conditions. Energy, 180, 626-639. doi:10.1016/j.energy.2019.05.062Van Leer, B. (1974). Towards the ultimate conservative difference scheme. II. Monotonicity and conservation combined in a second-order scheme. Journal of Computational Physics, 14(4), 361-370. doi:10.1016/0021-9991(74)90019-9Toro, E. F., Spruce, M., & Speares, W. (1994). Restoration of the contact surface in the HLL-Riemann solver. Shock Waves, 4(1), 25-34. doi:10.1007/bf01414629Courant, R., Friedrichs, K., & Lewy, H. (1928). �ber die partiellen Differenzengleichungen der mathematischen Physik. Mathematische Annalen, 100(1), 32-74. doi:10.1007/bf0144883

Comparative bio-accessibility, bioavailability and bioequivalence of quercetin, apigenin, glucoraphanin and carotenoids from freeze-dried vegetables incorporated into a baked snack versus minimally processed vegetables:Evidence from in vitro models and a human bioavailability study

The aim was to incorporate vegetables containing the phytochemicals quercetin, apigenin, glucoraphanin and carotenoids into a processed potato-based snack and assess their bioaccessibility and bioavailability. Three different processing routes were tested for incorporation and retention of phytochemicals in snacks using individually quick frozen or freeze-dried vegetables. No significant differences in the uptake or transport of quercetin or apigenin between a vegetable mix or snacks were observed using the CaCo-2 transwell model. Simulated in vitro digestions predicted a substantial release of quercetin and apigenin, some release of glucoraphanin but none for carotenes from either the snack or equivalent steamed vegetables. In humans, there were no significant differences in the bioavailability of quercetin, apigenin or glucoraphanin from the snack or equivalent steamed vegetables. We have shown that significant quantities of freeze-dried vegetables can be incorporated into snacks with good retention of phytochemicals and with similar bioavailability to equivalent steamed vegetables

Correlations for Wiebe function parameters for combustion simulation in two-stroke small engines

Combustion simulation in two-stroke engines becomes necessary not only for engine performance prediction but also for scavenge evaluation, since in-cylinder pressure and temperature are highly influenced by combustion process evolution. Combustion simulation by using a Wiebe function is appropriate to be included in a 1D engine code for providing design criteria with fast and accurate calculations; the main drawback is the determination of the four Wiebe parameters needed to build up the in-cylinder heat release. This paper deals with a detailed methodology for heat release determination in two-stroke engines under a wide range of running conditions; obtained empirical data will serve for building ad-hoc Wiebe functions, whose four parameters will be finally correlated with engine related parameters derived from 1D simulations. Two different engines, with three exhaust systems each, varying engine speed and spark-ignition timing were used to obtain correlations far from particular situations. A multiple regression analysis stated that charge density, residual gas fraction, spark timing and mean piston speed were the significant engine parameters that influence on Wiebe parameters. Finally, two scenarios were considered regarding Wiebe parameters: (a) specific correlations different for each engine gave coefficient of multiple determination values higher than 98% when predicting indicated mean effective pressure, (b) a global correlation used for both engines provided R2 values of 93% in the 50 cc and 91% in the 125 cc engine. © 2010 Elsevier Ltd. All rights reserved.Galindo Lucas, J.; Climent Puchades, H.; Pla Moreno, B.; Jimenez Macedo, VD. (2011). Correlations for Wiebe function parameters for combustion simulation in two-stroke small engines. Applied Thermal Engineering. 31:1190-1199. doi:10.1016/j.applthermaleng.2010.12.020S119011993

Bacterial DNAemia is associated with serum zonulin levels in older subjects

The increased presence of bacteria in blood is a plausible contributing factor in the development and progression of aging-associated diseases. In this context, we performed the quantification and the taxonomic profiling of the bacterial DNA in blood samples collected from forty-three older subjects enrolled in a nursing home. Quantitative PCR targeting the 16S rRNA gene revealed that all samples contained detectable amounts of bacterial DNA with a concentration that varied considerably between subjects. Correlation analyses revealed that the bacterial DNAemia (expressed as concentration of 16S rRNA gene copies in blood) significantly associated with the serum levels of zonulin, a marker of intestinal permeability. This result was confirmed by the analysis of a second set of blood samples collected from the same subjects. 16S rRNA gene profiling revealed that most of the bacterial DNA detected in blood was ascribable to the phylum Proteobacteria with a predominance of the genus Pseudomonas. Several control samples were also analyzed to assess the influence of contaminant bacterial DNA potentially originating from reagents and materials. The data reported here suggest that para-cellular permeability of epithelial (and, potentially, endothelial) cell layers may play an important role in bacterial migration into the bloodstream. Bacterial DNAemia is likely to impact on several aspects of host physiology and could underpin the development and prognosis of various diseases in older subjects

Analysis of shock capturing methods for chemical species transport in unsteady compressible flow

This paper presents a chemical species transport model to account for variable composition and gas properties along the flow path in internal combustion engines. The numerical solution to adapt the gas dynamic model to chemical species transport in boundary conditions by means of the Method of Characteristics and in volumes by means of a filling and emptying model is described. The performance for chemical species transport in 1D elementsof shock-capturing methods, such as the two-step Lax Wendroff method and the Sweby s TVD scheme considering several flux limiter definitions, is carried out by means of shocktube tests. The influence of the fluid modelling as perfect or non-perfect gas on the numerical methods features and the flow characteristics on shock-tube results are analysed.This work has been partially supported by the Spanish Ministerio de Ciencia e Innovacion through grant number DPI2010-20891-C02-02.Serrano Cruz, JR.; Climent, H.; Piqueras, P.; García Afonso, Ó. (2013). Analysis of shock capturing methods for chemical species transport in unsteady compressible flow. Mathematical and Computer Modelling. 57(7-8):1751-1759. https://doi.org/10.1016/j.mcm.2011.11.026S17511759577-