Effect of Increased Cabin Recirculation Airflow Fraction on Relative Humidity, CO2 and TVOC

In the CleanSky 2 ComAir study, subject tests were conducted in the Fraunhofer Flight Test Facility cabin mock-up. This mock-up consists of the front section of a former in-service A310 hosting up to 80 passengers. In 12 sessions the outdoor/recirculation airflow ratio was altered from today’s typically applied fractions to up to 88% recirculation fraction. This leads to increased relative humidity, carbon dioxide (CO2) and Total Volatile Organic Compounds (TVOC) levels in the cabin air, as the emissions by passengers become less diluted by outdoor, dry air. This paper describes the measured increase of relative humidity, CO2 and TVOC level in the cabin air for the different test conditions.

Optimal drainage cannula position in dual cannulation for veno-venous extracorporeal membrane oxygenation

Introduction: Recently, the use of veno-venous extracorporeal membrane oxygenation for adult patients with severe acute respiratory failure has increased. We previously investigated the optimal return cannula position; however, the optimal drainage cannula position has not yet been fully clarified. The aim of this study was to investigate the optimal drainage cannula position. Methods: Veno-venous extracorporeal membrane oxygenation was performed in four adult goats (mean body weight 59.6 ± 0.6 kg). The position of the drainage cannula was varied among the right atrium, the upper inferior vena cava, and the lower inferior vena cava, whereas the position of the return cannula was fixed in the superior vena cava. The recirculation fraction and arterial oxygen saturation and pressure (SaO2, PaO2) were measured in all drainage cannula positions. Results: In the lower inferior vena cava drainage cannula position, the recirculation fraction was the lowest. In the lower inferior vena cava, upper inferior vena cava, and right atrium drainage cannula positions at 3 L/min, SaO2 and PaO2 after 20 min were 92.9% ± 4.9% and 75.1 ± 26.0 mm Hg, 99.5% ± 0.5% and 113.8 ± 20.9 mm Hg, and 93.8% ± 6.2% and 91.9 ± 17.7 mm Hg, respectively. Conclusion: With respect to blood oxygenation, the optimal position for the drainage cannula was the upper inferior vena cava. These findings suggested that blood from the superior vena cava, inferior vena cava, and hepatic vein was most efficiently drained in the upper inferior vena cava cannula position.

Abstract P079: Cardiac Contractility in Response to Isoproterenol from Gravin Knockout (AKAP12) Mice

Gravin (AKAP12), one of the A-Kinase-Binding-Proteins (AKAPs), serves as a scaffold protein linking β 2 -adrenergic receptor (β 2 -AR), phosphatase 2B and several kinases including Protein Kinase A (PKA) and Protein Kinase C (PKC). The presence of gravin facilitates signal transduction of β 2 -AR and thus affects cardiac excitation-contraction coupling. We previously showed decreased cardiac hypertrophy, increased contractility and decreased arrhythmias in gravin-KO mice, following chronic β-AR stimulation. This response was associated with enhanced [Ca 2+ ] i homeostasis. Here, we test whether cardiac contraction is also affected in gravin knock-out (gravin-KO) mice. Trabeculae or small papillary muscles from the right ventricles were mounted between a force transducer and a motor arm, and superfused with K-H solution (pH 7.4) at room temperature. Developed force increased as external Ca 2+ ([Ca 2+ ] o ) was raised from 1 to 10 mM in both gravin-KO and wide-type (WT) muscles. Developed force and intracellular Ca 2+ transient (Ca 2+ i ) increased in a dose dependent manner as [Ca 2+ ] o was raised. Gravin-KO muscles had lower Ca 2+ i at any given [Ca 2+ ] o , but had similar force at [Ca 2+ ] o >4.0 mM; at higher [Ca 2+ ] o s, developed forces was significantly lower. Isoproterenol (ISO, 0.05-200nM) increased force and Ca 2+ i in both groups of muscles. However, force and Ca 2+ i started to blunt in gravin-KO muscle at higher ISO doses and became significantly lower at ISO does >50 nM. Both force and Ca 2+ i were lower at a given rest interval in gravin-KO muscles with no changes in recirculation fraction (RF). These results show that gravin-KO muscles maintain their response to both Ca 2+ and ISO with reduced capacity at higher doses, and to rest potentiations with lower magnitudes, but with no changes in recirculation fraction of Ca 2+ through the sarcoplasmic reticulum (SR). These findings suggest: (1) gravin-KO muscles may likely have smaller Ca 2+ content in the SR; (2) gravin plays an important modulatory role in the argumentation of force by Ca 2+ and β 2 -AR stimulation; (3) at physiological [Ca 2+ ] o , gravin-KO increases myofilament Ca 2+ responsiveness. Ongoing experiments are focused on changes myofilament Ca 2+ responsiveness in gravin-KO mice.

Closed-Loop Control Framework for Fuel-Flexible Combustion of Biodiesel Blends

This paper presents a closed-loop control framework for fuel-flexible combustion control of biodiesel blends. This framework consists of two parts: blend detection and blend accommodation. Blend detection can be accomplished by an experimentally-validated dynamic estimator using exhaust oxygen and air-fuel ratio information. Blend accommodation can be accomplished by changing the control variables that the engine control module uses, namely, replacing exhaust gas recirculation fraction with combustible oxygen mass fraction, replacing total injected fuel mass with total injected fuel energy, and replacing start of main injection timing with end of main injection timing. With the conventional control structure it is experimentally shown that pure biodiesel (B100) produced 38% more brake specific nitrogen oxides (BSNOx) than pure conventional diesel (B0). With the new proposed structure, B100 produced not only lower BSNOx than B0, but also higher torque, higher brake thermal efficiency, lower particulate matter, and lower combustion noise than B0. Comparable experimental results are also presented for B5 and B20 blends.

Contractile reserve but not tension is reduced in monocrotaline-induced right ventricular hypertrophy

The objective of this study was to evaluate the role of right ventricular hypertrophy on developed tension (Fdev) and contractile reserve of rat papillary muscle by using a model of monocrotaline (Mct)-induced pulmonary hypertension. Calcium handling and the influence of bicarbonate ([Formula: see text]) were also addressed with the use of two different buffers ([Formula: see text] and HEPES). Wistar rats were injected with either Mct (40 mg/kg sc) or vehicle control (Con). Isometrically contracting right ventricular papillary muscles were studied at 80% of the length of maximal developed force. Contractile reserve (1 – Fdev/Fmax) was calculated from Fdev and maximal tension (Fmax). Calcium recirculation was determined with postextrasystolic potentiation. Both groups of muscles were superfused with either [Formula: see text] (Con-B and Mct-B, both n = 6) or HEPES (Con-H and Mct-H, both n = 6) buffer. With hypertrophy, contractions were slower but Fdev was not changed. However, Fmax was decreased ( P < 0.05). With [Formula: see text], Fmax decreased from 23.8 ± 6.5 mN·mm–2 in Con-B, to 13.7 ± 3.3 mN·mm–2 in Mct-B. With HEPES, it decreased from 16.3 ± 3.5 mN·mm–2 ( n = 6, Con-H) to 8.3 ± 1.6 mN·mm–2 (Mct-H). Contractile reserve during hypertrophy was therefore also decreased ( P < 0.05). With [Formula: see text], it decreased from 0.73 ± 0.03 (Con-B) to 0.55 ± 0.04 (Mct-B). With HEPES, it decreased ( P < 0.001) from 0.64 ± 0.07 (Con-H) to 0.19 ± 0.06 (Mct-H). The recirculation fraction decreased ( P < 0.05) from 0.59 ± 0.04 in Con-B to 0.44 ± 0.04 in Mct-B. We conclude that contractile reserve and recirculation fraction are impaired during hypertrophy, with a stronger effect under HEPES than [Formula: see text] superfusion.