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https://www.readbyqxmd.com/read/29656786/numerical-investigation-of-band-spreading-generated-by-flow-through-needle-and-fixed-loop-sample-injectors
#1
Sander Deridder, Gert Desmet, Ken Broeckhoven
The present study reports on a computational fluid dynamics study of the band broadening occurring in injector systems frequently used in contemporary liquid chromatography instruments. The aim of this work is to determine band broadening originating purely from the injection volume in absence of any other possible contribution (e.g. band broadening due to the injection valve) and to unravel the mechanism behind it. Simulations of the dispersion process in flow through needle injectors were performed. In addition, fixed loop injectors were also simulated and comparison with flow through needle injectors was made...
April 3, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29590412/screening-spirometry-in-military-personnel-correlates-poorly-with-exercise-tolerance-and-asthma-history
#2
David M F Anderson, Nicholas R Ondrasik, Frederic A Rawlins, Joshua A Lospinoso, Thomas B Zanders, Michael J Morris
BACKGROUND: Spirometry is an easy-to-perform test for evaluating pulmonary symptoms but has several limitations to include adequate test performance for valid results. Spirometry is not recommended to screen a general population for evidence of pulmonary disease unless symptoms are present or longitudinal screening is done for potential occupational exposures. METHODS: A single-spirometry examination was performed on 900 active duty Army soldiers, ages 18-35 yr, without documented respiratory disease...
March 26, 2018: Military Medicine
https://www.readbyqxmd.com/read/29568740/feasibility-of-computational-fluid-dynamics-for-evaluating-the-intraventricular-hemodynamics-in-single-right-ventricle-based-on-echocardiographic-images
#3
Li-Jun Chen, Zhi-Rong Tong, Qian Wang, Yu-Qi Zhang, Jin-Long Liu
This study introduced a combined computational fluid dynamics (CFD) and echocardiography methodology to simulate blood flow in the single right ventricle (SRV) and normal ventricles to study the intraventricular flow. Derived from echocardiographic image loops, CFD-based three-dimensional (3D) flow models of normal subject's left ventricle (LV) and right ventricle (RV) and SRV with and without heart failure at three characteristic diastolic statuses were reconstructed. The CFD derived morphological and functional measurements in normal ventricles and the SRV were validated with echocardiography...
2018: BioMed Research International
https://www.readbyqxmd.com/read/29568152/comparative-piv-and-lda-studies-of-newtonian-and-non-newtonian-flows-in-an-agitated-tank
#4
Anna Story, Zdzisław Jaworski, Mark J Simmons, Emilia Nowak
The paper presents results of an experimental study of the fluid velocity field in a stirred tank equipped with a Prochem Maxflo T (PMT) type impeller which was rotating at a constant frequency of N  = 4.1 or 8.2 s-1 inducing transitional ( Re  = 499 or 1307) or turbulent ( Re  = 2.43 × 104 ) flow of the fluid. The experiments were performed for a Newtonian fluid (water) and a non-Newtonian fluid (0.2 wt% aqueous solution of carboxymethyl cellulose, CMC) exhibiting mild viscoelastic properties. Measurements were carried out using laser light scattering on tracer particles which follow the flow (2-D PIV)...
2018: Chemické Zvesti
https://www.readbyqxmd.com/read/29546045/ventilator-flow-data-predict-bronchopulmonary-dysplasia-in-extremely-premature-neonates
#5
Mariann H Bentsen, Trond Markestad, Thomas Halvorsen
Early prediction of bronchopulmonary dysplasia (BPD) may facilitate tailored management for neonates at risk. We investigated whether easily accessible flow data from a mechanical ventilator can predict BPD in neonates born extremely premature (EP). In a prospective population-based study of EP-born neonates, flow data were obtained from the ventilator during the first 48 h of life. Data were logged for >10 min and then converted to flow-volume loops using custom-made software. Tidal breathing parameters were calculated and averaged from ≥200 breath cycles, and data were compared between those who later developed moderate/severe and no/mild BPD...
January 2018: ERJ Open Research
https://www.readbyqxmd.com/read/29512293/adaptation-to-acute-pulmonary-hypertension-in-pigs
#6
Mare Mechelinck, Marc Hein, Sven Bellen, Rolf Rossaint, Anna B Roehl
The extent of right ventricular compensation compared to the left ventricle is restricted and varies among individuals, which makes it difficult to define. While establishing a model of acute pulmonary hypertension in pigs we observed two different kinds of compensation in our animals. Looking deeper into the hemodynamic data we tried to delineate why some animals could compensate and others could not. Pulmonary hypertension (mean pressure 45 mmHg) was induced gradually by infusion of a stable thromboxane A2 analogue U46619 in a porcine model (n = 22)...
March 2018: Physiological Reports
https://www.readbyqxmd.com/read/29480841/evaluation-of-the-anatomic-and-hemodynamic-abnormalities-in-tricuspid-atresia-before-and-after-surgery-using-computational-fluid-dynamics
#7
Li-Jun Chen, Yu-Qi Zhang, Zhi-Rong Tong, Ai-Min Sun
Analysis of hemodynamics inside tricuspid atresia (TA) chamber is essential to the understanding of TA for optimal treatment. In this study, we introduced a combined computational fluid dynamics (CFD) to simulate blood flow in the left ventricle (LV) to study the diastolic flow changes in TA.Real-time 3-dimentional echocardiography loops (ECHO) were acquired in normal control group, in TA patients before surgery (pre-op group) and after surgery (post-op group). ECHO loops were reconstructed and simulated by CFD, the geometric, volumetric changes, and vortices in the LV were studies and compare among 3 groups...
January 2018: Medicine (Baltimore)
https://www.readbyqxmd.com/read/29452928/comprehensive-on-line-two-dimensional-liquid-chromatography-%C3%A3-supercritical-fluid-chromatography-with-trapping-column-assisted-modulation-for-depolymerised-lignin-analysis
#8
Mingzhe Sun, Margareta Sandahl, Charlotta Turner
Lignin depolymerisation produces a large variety of low molecular weight phenolic compounds that can be upgraded to value-added chemicals. Detailed analysis of these complex depolymerisation mixtures is, however, hampered by the lack of resolving power of traditional analysis techniques. In this study, a novel online comprehensive two-dimensional reversed-phase liquid chromatography (RPLC) × supercritical fluid chromatography (SFC) method with trapping column interface was developed for the separation of phenolic compounds in depolymerised lignin samples...
February 6, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29437172/closed-loop-feedback-control-for-microfluidic-systems-through-automated-capacitive-fluid-height-sensing
#9
L R Soenksen, T Kassis, M Noh, L G Griffith, D L Trumper
Precise fluid height sensing in open-channel microfluidics has long been a desirable feature for a wide range of applications. However, performing accurate measurements of the fluid level in small-scale reservoirs (<1 mL) has proven to be an elusive goal, especially if direct fluid-sensor contact needs to be avoided. In particular, gravity-driven systems used in several microfluidic applications to establish pressure gradients and impose flow remain open-loop and largely unmonitored due to these sensing limitations...
February 13, 2018: Lab on a Chip
https://www.readbyqxmd.com/read/29405616/flow-volume-loops-measured-with-electrical-impedance-tomography-in-pediatric-patients-with-asthma
#10
Chuong Ngo, Falk Dippel, Klaus Tenbrock, Steffen Leonhardt, Sylvia Lehmann
BACKGROUND: Electrical impedance tomography (EIT) provides information on global and regional ventilation during tidal breathing and mechanical ventilation. During forced expiration maneuvers, the linearity of EIT and spirometric data has been documented in healthy persons. The present study investigates the potential diagnostic use of EIT in pediatric patients with asthma. METHODS: EIT and spirometry were performed in 58 children with asthma (average age ± SD: 11...
February 6, 2018: Pediatric Pulmonology
https://www.readbyqxmd.com/read/29394944/windkessel-model-of-hemodynamic-state-supported-by-a-pulsatile-ventricular-assist-device-in-premature-ventricle-contraction
#11
Keun Her, Joon Yeong Kim, Ki Moo Lim, Seong Wook Choi
BACKGROUND: Counter-pulsation control (CPC) by ventricular assist devices (VADs) is believed to reduce cardiac load and increase coronary perfusion. However, patients with VADs have a higher risk of arrhythmia, which may cause the CPC to fail. Consequently, CPC has not been applied by VADs in clinical practice. The phase-locked loop (PLL) algorithm for CPC is readily implemented in VADs; however, it requires a normal, consistent heartbeat for adequate performance. When an arrhythmia occurs, the algorithm maintains a constant pumping rate despite the unstable heartbeat...
February 2, 2018: Biomedical Engineering Online
https://www.readbyqxmd.com/read/29365118/initial-in-vitro-testing-of-a-paediatric-continuous-flow-total-artificial-heart
#12
Kiyotaka Fukamachi, Jamshid H Karimov, David J Horvath, Gengo Sunagawa, Nicole A Byram, Barry D Kuban, Nader Moazami
OBJECTIVES: Mechanical circulatory support has become standard therapy for adult patients with end-stage heart failure; however, in paediatric patients with congenital heart disease, the options for chronic mechanical circulatory support are limited to paracorporeal devices or off-label use of devices intended for implantation in adults. Congenital heart disease and cardiomyopathy often involve both the left and right ventricles; in such cases, heart transplantation, a biventricular assist device or a total artificial heart is needed to adequately sustain both pulmonary and systemic circulations...
January 19, 2018: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/29331222/on-tubing-fluorescence-measurements-of-the-band-broadening-of-contemporary-injectors-in-ultra-high-performance-liquid-chromatography
#13
Ken Broeckhoven, Kim Vanderlinden, Davy Guillarme, Gert Desmet
We report on a detailed study of the injection contribution to band broadening in contemporary UHPLC-instruments, using either flow-through needle or fixed loop injection (full loop). Using on-tubing fluorescence measurements at the outlet of the injector valve, very localized and undisturbed measurements were obtained. Varying both the flow rate and the injected volume allowed to split the injection variance (σV 2 ,inj ) in a volumetric component (related to the amount injected) and a hydrodynamic component (related to the flow rate)...
February 2, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29330837/computer-simulated-modeling-of-healthy-and-diseased-right-ventricular-and-pulmonary-circulation
#14
Jody Chou, Joseph B Rinehart
We have previously developed a simulated cardiovascular physiology model for in-silico testing and validation of novel closed-loop controllers. To date, a detailed model of the right heart and pulmonary circulation was not needed, as previous controllers were not intended for use in patients with cardiac or pulmonary pathology. With new development of controllers for vasopressors, and looking forward, for combined vasopressor-fluid controllers, modeling of right-sided and pulmonary pathology is now relevant to further in-silico validation, so we aimed to expand our existing simulation platform to include these elements...
January 12, 2018: Journal of Clinical Monitoring and Computing
https://www.readbyqxmd.com/read/29203113/improved-separation-by-at-column-dilution-in-preparative-hydrophilic-interaction-chromatography
#15
Geoffrey Jaffuel, Laura Chappuis, Davy Guillarme, Ted C J Turlings, Gaétan Glauser
We evaluated at-column dilution (ACD) as a possible approach to reduce peak distortion caused by the injection of strong solvents in preparative hydrophilic interaction chromatography (HILIC). Three model compounds, namely uridine, cytidine and guanosine were selected and injected either in conventional or ACD conditions, using various proportions of water and acetonitrile in the sample diluent. Plate number and peak capacity were systematically investigated under both isocratic and gradient elution conditions, respectively...
January 12, 2018: Journal of Chromatography. A
https://www.readbyqxmd.com/read/29193495/premature-birth-affects-the-degree-of-airway-dysanapsis-and-mechanical-ventilatory-constraints
#16
Joseph W Duke, Igor M Gladstone, A William Sheel, Andrew T Lovering
What is the central question of this study? Adult survivors of preterm birth without (PRE) and with bronchopulmonary dysplasia (BPD) have airflow obstruction at rest and significant mechanical ventilatory constraints during exercise compared with those born at full term (CON). Do PRE/BPD have smaller airways, indexed via the dysanapsis ratio, than CON? What is the main finding and its importance? The dysanapsis ratio was significantly smaller in BPD and PRE compared with CON, with BPD having the smallest dysanapsis ratio...
February 1, 2018: Experimental Physiology
https://www.readbyqxmd.com/read/29190612/assessment-of-bronchial-obstruction-using-lateral-pressure-measurement-during-bronchoscopy
#17
Hiroki Nishine, Takehiko Hiramoto, Takeo Inoue, Naoki Furuya, Hirotaka Kida, Hiroshi Handa, Seiichi Nobuyama, Masamichi Mineshita, Teruomi Miyazawa
BACKGROUND: In patients with bronchial obstruction estimating the location of the maximal obstruction is crucial for guiding interventional bronchoscopy. However, flow-volume curves cannot discriminate between the right and left lungs. OBJECTIVES: The aim of this study was to physiologically evaluate bronchial obstruction during interventional bronchoscopy. METHODS: We prospectively measured lateral airway pressure (Plat) at either side of the obstruction using a double-lumen catheter (pressure-pressure [P-P] curve) simultaneously to assess the degree of bronchial obstruction in 22 patients...
2018: Respiration; International Review of Thoracic Diseases
https://www.readbyqxmd.com/read/29097129/recycling-potential-of-post-consumer-plastic-packaging-waste-in-finland
#18
Helena Dahlbo, Valeria Poliakova, Ville Mylläri, Olli Sahimaa, Reetta Anderson
Recycling of plastics is urged by the need for closing material loops to maintain our natural resources when striving towards circular economy, but also by the concern raced by observations of plastic scrap in oceans and lakes. Packaging industry is the sector using the largest share of plastics, hence packaging dominates in the plastic waste flow. The aim of this paper was to sum up the recycling potential of post-consumer plastic packaging waste in Finland. This potential was evaluated based on the quantity, composition and mechanical quality of the plastic packaging waste generated by consumers and collected as a source-separated fraction, within the mixed municipal solid waste (MSW) or within energy waste...
January 2018: Waste Management
https://www.readbyqxmd.com/read/29080776/comprehensive-computational-assessment-of-blood-flow-characteristics-of-left-ventricle-based-on-in-vivo-mri-in-presence-of-artificial-myocardial-infarction
#19
Ali Imanparast, Nasser Fatouraee, Farhad Sharif
BACKGROUND: Understanding the effects of cardiac diseases on the heart's functionality which is the purpose of many biomedical researches, directly affects the diagnostic and therapeutic methods. Myocardial infarction (MI) is a common complication of cardiac ischemia, however, the impact of MI on the left ventricle (LV) flow patterns has not been widely considered by computational fluid dynamics studies thus far. METHODS: In this study, we present an insightful numerical method that creates an artificial MI on an image-based fluid-structure interactional model of normal LV to investigate its influence on the flow in comparison with the normal case...
December 2017: Mathematical Biosciences
https://www.readbyqxmd.com/read/29067926/rare-tracheal-tumor-solitary-plasmacytoma
#20
R Stevic, M Ercegovac, J Stojšić, N Čolić
Primary tracheal tumors are rare and trachea is an exceedingly rare site of extramedullary plasmacytoma (EMP). We report a case of solitary tracheal plasmacytoma causing symptoms of airway obstruction in a 59-year-old man. Flow/volume loop indicated the fixed central airway obstruction. Computerized tomography and bronchoscopy demonstrated a sessile tumor on posterior tracheal wall obstructing 80% of the lumen. Partial tracheal resection with T-T anastomosis was performed. Pathologic analysis of resected mass revealed EMP...
October 23, 2017: Journal of Postgraduate Medicine
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