Orifice Dimension Research Articles

Left atrial appendage orifice dimensions in Japanese atrial fibrillation population measured by multiplane transesophageal echocardiography.

Successful implantation of the WATCHMAN device requires an accurate understanding of left atrial appendage (LAA) anatomy and orifice dimensions. Racial differences are observed in LAA size when comparing Asians with non-Asians. A total of 170 patients (123 male, 67.4 ± 9.2years) with paroxysmal or persistent atrial fibrillation (AF) underwent transesophageal echocardiography before catheter ablation or cardioversion (September 2018 to September 2019). As per the recommendations of the WATCHMAN device, the maximal LAA ostial diameters were measured at multiplane angles of 0°, 45°, 90°, and 135°. The majority of patients (121/170, 71%) had an LAA orifice size within 17-25mm. Fifteen (8.8%) patients had undersized (< 17mm) and eight (0.5%) had oversized (> 31mm) LAA. One patient in this population had no LAA. LAA size was significantly larger in patients with persistent AF than in those with paroxysmal AF (23.3 ± 4.2mm vs. 20.0 ± 3.0mm, p < 0.001) and in male patients than in female patients (22.4 ± 4.2 vs. 20.9 ± 3.7mm, p = 0.03). LAA orifice dimension was significantly correlated with CHADS2 score, the left atrial volume (LAV), E/e', and the left ventricular ejection fraction. Persistent AF, body mass index, and LAV were independently associated with LAA orifice dimension in multivariate analysis. This study demonstrated the distribution of LAA orifice dimension in the Japanese AF patients. This finding should be used as a reference to understand the racial characteristics of LAA size for the WATCHMAN procedure.

Intravascular ultrasound for peri-procedural geometric orifice area measurement during transcatheter pulmonary valve replacement

Abstract Introduction Large imaging filed intravascular ultrasound (IVUS) offering superior online tomographic perspective and visual accuracy could guide transcatheter pulmonary valve replacement (TPVR) for right ventricular outflow tract (RVOT) insufficiency. It is unknown whether geometric orifice area (GOA) measured by IVUS corresponds with effective orifice area (EOA) measure by transthoracic echocardiography (TTE) after successful TPVR. Purpose To compare minimal inner-leaflets cross-sectional area delineated in systole (min GOA) measured by IVUS versus EOA calculated = right ventricle stroke volume (measured in baseline cardiac magnetic resonance) / pulmonary valve velocity time integral (measured early post-procedure by Vivid e95). Methods After successful TPVR a 10MHz Vision PV 0.035" (60mm imaging field) IVUS catheter was slowly pulled from the distal pulmonary artery to the right ventricle with continuous imaging of RVOT. IVUS measurements included inner-valve dimension for several evenly spaced cross-sections along the entire length and perpendicular to RVOT long axis. Measured were outer-frame diameters (minimal and maximal) and its cross-sectional area, and cross-sectional area of the visual orifice (min GOA) identified exclusively at the coaptation site (Fig 1). Results There were 11 pts (median age 30 [25–36] yrs, 4 ♀, all but one with Tetralogy of Fallot) who had undergone prior corrective surgery (5 transannular patch, 2 bioprosthetic valve or 4 pulmonary homograft). Overall, 176 cross-sections were analyzed. Overall, min GOA measured 3.7±1.0cm2, and was 68%±9% of the valve-outer area (5.5±1.5cm2). It was substantially larger than calculated EOA (3.7±1.0cm2 vs 2.0±0.5cm2; p&amp;lt;0.001). The ratio of max/min GOA diameter was 1.11±0.11 signifying low eccentricity and was not related to EAO. Conclusions After successful balloon-expandable valve implantation to treat RVOT insufficiency, geometric orifice dimension was significantly smaller then outer valve frame dimension. Visual measure of geometric orifice area during the procedure using IVUS documented its circularity and indicated that it was larger than EOA calculated upon functional measure. Funding Acknowledgement Type of funding sources: Public hospital(s). Main funding source(s): This work was supported by the research grant (2.4/VI/18) founded by the National Institute of Cardiology in Warsaw (Poland). IVUS visualization of ES3.

Optimization and Experimentation of Modified Throttling Calorimeter

Steam plays a vital role in the industrial revolution and is a major source of power generation in steam engines or steam turbine. Thus, it becomes necessary to maintain steam as dry as possible and it is necessary to monitor steam quality on a regular basis. The most commonly used method in determining steam quality is Throttling calorimeter. Here existing throttling calorimeter is designed for determining steam quality within a pressure range of 20 – 25 bar. This existing calorimeter is optimized for monitoring steam quality within a range of 4 – 12 bar gauge pressure. Pipe and orifice dimension of the calorimeter is calculated for a given flow rate of steam by using ISO norms and Bernoulli’s principle. After conducting multiple trials on newly designed model test rig it is found that the 4 mm orifice diameter model gives the greater consistency of results and it is considered to be an optimized model.

Evaluation of TLCD Damping Factor from FRF Measurement Due to Variation of the Fluid Viscosity

&lt;p class="TTPAbstract"&gt;Tuned Liquid Column Damper (TLCD) has become an alternative solution for reducing low frequency vibration response of machines and structures. This is not surprisingly that the damper has simply structure and low maintenance cost. The main disadvantage of using TLCD is the complexity in controlling TLCD damping factor experimentally. Theoretically, damping factor can be controlled by adjusting the orifice dimension. However, this method is time consuming and not appropriate conducted in the real application. A more simply method for adjusting TLCD damping factor is by varying the fluid viscosity. This research is aimed to evaluate the effect of fluid viscosity to the damper performance. Two DOF shear structure with TLCD is used as the experimental model. Several TLCD fluids with different viscosity are evaluated. Evaluation of TLCD damping factor due to variation of the fluid viscosity is conducted by comparing the Frequency Response Function (FRF) obtained from the experimental data.&lt;/p&gt;

Evaluation of TLCD Damping Factor from FRF Measurement Due to Variation of the Fluid Viscosity

&lt;p class="TTPAbstract"&gt;Tuned Liquid Column Damper (TLCD) has become an alternative solution for reducing low frequency vibration response of machines and structures. This is not surprisingly that the damper has simply structure and low maintenance cost. The main disadvantage of using TLCD is the complexity in controlling TLCD damping factor experimentally. Theoretically, damping factor can be controlled by adjusting the orifice dimension. However, this method is time consuming and not appropriate conducted in the real application. A more simply method for adjusting TLCD damping factor is by varying the fluid viscosity. This research is aimed to evaluate the effect of fluid viscosity to the damper performance. Two DOF shear structure with TLCD is used as the experimental model. Several TLCD fluids with different viscosity are evaluated. Evaluation of TLCD damping factor due to variation of the fluid viscosity is conducted by comparing the Frequency Response Function (FRF) obtained from the experimental data.&lt;/p&gt;

Large-scale experiments on the behaviour of a generalised Oscillating Water Column under random waves

This work investigates wave reflection and loading on a generalised Oscillating Water Column (OWC) wave energy converter by means of large scale (approximately 1:5–1:9) experiments in the Grosse Wellenkanal (GWK), in which variation of both still water depth and orifice (PTO) dimension are investigated under random waves. The model set-up, calibration methodology, reflection analyses and loadings acting on the OWC are reported. On the basis of wave reflection analysis, the optimum orifice is defined as that restriction which causes the smallest reflection coefficient and thus the greatest wave energy extraction. Pressures on the front wall, rear wall and chamber ceiling are measured. Maximum pressures on the vertical walls, and resulting integrated forces, are compared with available formulations for impulsive loading prediction, which showed significant underestimation for heaviest loading conditions.The present study demonstrates that a OWC structure can serve as a wave absorber for reducing wave reflection. Thus it can be integrated in vertical wall breakwaters, in place of other perforated low reflection alternatives. The possibility to convert air kinetic into electric energy, by means of a turbine, may give an additional benefit. Thus the installation of such kind of energy converters becomes interesting also in low energy seas.

Description and preliminary results of a 100 square meter rain gauge

Summary Rainfall is one of the most crucial processes in hydrology, and the direct and indirect rainfall measurement methods are constantly being updated and improved. The standard instrument used to measure rainfall rate and accumulation is the rain gauge, which provides direct observations. Though the small dimension of the orifice allows rain gauges to be installed anywhere, it also causes errors due to the splash and wind effects. To investigate the role of the orifice dimension, this study, for the first time, introduces and demonstrates an apparatus for observing rainfall called a giant-rain gauge that is characterised by a collecting surface of 100 m 2 . To discuss the new instrument and its technical details, a preliminary analysis of 26 rainfall events is provided. The results suggest that there are significant differences between the standard and proposed rain gauges. Specifically, major discrepancies are evident for low time aggregation scale (5, 10, and 15 min) and for high rainfall intensity values.

Hydrogel-swelling driven delivery device for corrosion resistance of metal in water.

Corrosion on steel and copper pipes in industry can trigger pollution and weakness due to undesired chemical and biochemical reactions. Too much or too little inhibitor can decrease its efficiency, even causing waste and pollution. In this contribution, an innovative delivery device driven by hydrogel swelling, mainly consisting of a semi-permeable membrane, a hydrogel-swelling force drive and a release orifice, was developed to control the release of inhibitor in a water system at a constant rate, leading the amount of inhibitor to maintain a proper concentration. The effects of hydrogel mass and orifice dimension on release property were studied for controlling release rate. Moreover, a weight loss experiment on carbon steels was carried out to show the incredible anti-corrosion function of the system.

Modified vibrating-mesh nozzles for advanced spray-drying applications

This work describes uniform polymer coatings allowing for an adjustment of the orifice dimension of vibrating-mesh nozzles and therefore, size of emerging formulation droplets and dried particles, which is of general interest for diverse spray-drying applications.Chemical vapor deposition of poly(p-xylylene) (PPXN) on aperture templates of the B-90 spray-dryer (orifice diameters: ∼4.0μm) caused a reduction of the opening cross-sections of ∼50%. Thus, a more efficient formulation atomization was observed (finer droplets). Likewise, application of PPXN-coated, rather than plain nozzles, resulted in significantly smaller (particle diameter: 1.3 vs. 3.6μm) and narrower distributed (span: ∼1.4 vs. ∼1.8) sildenafil-loaded poly(lactide-co-glycolide) microparticles. Prediction of the size of spray-dried microparticles using the size results of atomized droplets (“residual core method”) was shown to be in agreement with the observed values. Formulations prepared with plain and PPXN-coated nozzles exhibited a sustained sildenafil release profile with mean dissolution times of ∼1.5 and ∼4.0h, respectively.Regardless of the starting aperture template, any desired orifice dimension and therefore, dried particle size could be achieved by generating adequate polymer deposits.

Combined Catheter Ablation for Atrial Fibrillation and Watchman® Left Atrial Appendage Occlusion Procedures: A Single Centre Experience.

Background Patients with atrial fibrillation (AF) may be interested in undergoing concomitant interventions of left atrial catheter ablation and device occlusion of the left atrial appendage (LAA). We report on the feasibility and outcome of combined procedures in a single centre case series. Methods Twenty-six patients underwent either first time or redo pulmonary vein isolation (PVI) procedures followed by successful implant of a Watchman® device. Results All procedures were uncomplicated with a mean case time of 233 ± 38 minutes. Maximal LAA orifice dimension was smaller in 3 of 26 patients post PVI (range 1mm) than on the pre-procedural transoesophageal echocardiogram (TOE). A new peri-device leak of maximum 3mm was noted in 5 of 26 patients at 6 week follow-up TOE, but resolved in 4 by the 6 month follow-up. Conclusion Combined procedures for catheter ablation for AF and Watchman® LAA implant appear to be feasible and safe with satisfactory occlusion of the LAA maintained at follow-up.

Anatomical analysis of the left atrial appendage using segmented, three-dimensional cardiac CT: a comparison of patients with paroxysmal and persistent forms of atrial fibrillation

Successful implantation of percutaneous left atrial appendage (LAA) occlusion devices requires an accurate understanding of LAA anatomy and orifice dimensions. We sought to quantitatively compare LAA anatomy in patients with paroxysmal and persistent patterns of atrial fibrillation (AF). Fifty-nine consecutive patients undergoing catheter ablation for AF underwent pre-procedural multislice cardiac computed tomography (CT) scans. Maximal LAA orifice dimensions and left atrial and LAA volumes were measured from three-dimensional segmented CT reconstructions. Thirty-six patients with paroxysmal and 23 with persistent AF were analysed. The mean maximal LAA orifice dimension was larger in persistent (27.2 ± 4 mm) than paroxysmal AF (22.9 ± 3 mm, p < 0.001). A strong correlation was found between both increasing LAA volume (r = 0.76), maximal LAA orifice dimension (r = 0.63) and left atrial volume. Increased LAA orifice dimension is associated with left atrial enlargement in AF. This finding may impact LAA occlusion device sizing.

Design and Performance Testing of Three Dimensional Trapezia Structure for Fabric Keyboard Switch

Fabric keyboard is a field of smart textile. It can overcome many disadvantages of conventional keyboard. In order to study the fabric keyboard switch, trapezia structures of two kinds of orifice dimension are designed for example 8 wefts and 16 wefts. Different roots of conductive wires are woven into the down layer of the orifice part for each kind of orifice dimension. 4 and 8 roots of wires are woven for 8 wefts. 4, 8 and 16 roots of wires are woven for 16wefts. Then the immediate regain, connection pressure, connection ratio and contact resistance are tested and analyzed for every kind of fabric keyboard switch. It is concluded that 8 wefts orifice dimension and 8 roots of wires woven into the down layer of the orifice part is a better project. These findings may assist in recommendations regarding the further development of flexible fabric keyboard.

Three Layers Weaved once Structure Design and Performance Testing for Fabric Keyboard Switch

Flexible fabric keyboard is a field of smart textile. It can overcome traditional horniness keyboard can’t be foldable and washing. In this laboratory study there is Three Layers Weaved Once structure designed which consists of three kinds of orifice dimension, for example 4 wefts, 8 wefts and 12 wefts. At the same time three kinds of conductive filaments number combined are planed for each orifice dimension. There are 1, 4 and 8 roots of filaments combined together so that contact areas of the conductive material are changed. Then the immediate regain, connection pressure and connection ratio are tested and analyzed for every kind of fabric keyboard switch. It is concluded that 4 wefts orifice dimension and 4 roots of filaments combined is a better project. These findings may assist in recommendations regarding the further development of flexible fabric keyboard. The fabric keyboard switch forms the foundation for many smart textile applications.

Choked flow mechanism of HFC-134a flowing through short-tube orifices

This paper is a continuation of the author’s previous work. New experimental data on the occurrence of choked flow phenomenon and mass flow rate of HFC-134a inside short-tube orifices under choked flow condition are presented. Short-tube orifices diameters ranging from 0.406mm to 0.686mm with lengths ranging from 1mm to 3mm which can be applied to a miniature vapour-compression refrigeration system are examined. The experimental results indicated that the occurrence of choked flow phenomena inside short-tube orifices is different from that obtained from short-tube orifice diameters of greater than 1mm, which are typically used in air-conditioner. The beginning of choked flow is dependent on the downstream pressure, degree of subcooling, and length-to-diameter ratio. Under choked flow condition, the mass flow rate is greatly varied with the short-tube orifice dimension, but it is slightly affected by the operating conditions. A correlation of mass flow rate through short-tube orifices is proposed in terms of the dimensionless parameters. The predicted results show good agreement with experimental data with a mean deviation of 4.69%.

Valvular Regurgitation Impact on Left Ventricular 2-Dimensional and Doppler Echocardiographic Indices in Patients With Essential Hypertension

BackgroundBlacks have both a higher hypertension prevalence and accelerated cardiac end organ damage. Because blacks also have a higher prevalence of valvular heart disease, which occurs at a younger age than for whites, we further examined the contribution of valvular regurgitation to the severity of hypertensive heart disease in Nigerians. MethodsWe evaluated and compared echocardiograph-ic indexes in 75 essential hypertensive Nigerians with (n = 48) and without (n = 27) valvular regurgitations. Demographic and echocardiographic indices, as well as the types and severity of valvular lesions were compared between the groups using bivariate logistic regression and analysis of variance. ResultsThe 2 groups were of similar demographics, but those with regurgitations had larger cardiac size (p < .05), greater mass (147 ± 31 vs 122 ± 32 g/m2, p = .01) higher volume (p < .01), and left atrial size (35.6 ± 4.6 vs 33.3 ± 4.6 mm, p < .05). Atrial size, cardiac volume, and dimension were independent correlates/predictors of regurgitation occurrence. Relative wall thickness of at least 0.6 was more common in regurgitation patients. Cardiac mass was correlated to increasing age (r = 0.23, p = .043). The valvular lesions frequencies were aortic regurgitation, 8; mitral regurgita-tion, 22; and mixed, 18. The aortic orifice dimension was significantly different among the regurgitant cases, highest in aortic regurgitation (p = .001). Aortic orifice dimension increased with hypertension duration (p = .028). ConclusionsRegurgitant lesions are common and occur early in hypertensive Africans. Apparently mild valvular regurgitation may accentuate preclinical concentric hypertrophy in hypertensive blacks.

Control of nitrogen flux for growth of cubic GaN on 3C-SiC/Si by RF-MBE

The enhancement of the production rate of nitrogen radical from a radio frequency (RF) discharge plasma is reported through the application of a DC magnetic field under RF-ECR (electron cyclotron resonance of RF) condition. High efficiency of the nitrogen radical production was realized by an optimum magnetic field for the resonance of about 0.5 mT for the electron energy of 2 eV for the 13.56-MHz discharge. The effect of controlling the divergence of the nitrogen radical flux by changing the orifice dimension was studied by measuring the color change of interference due to the film thickness. The aspect ratio of the orifice hole and the distribution of hole position determined the flux diversity. Combinatorial methodology, which realizes various III/V flux ratio without substrate rotation due to non-uniform flux, was used to study the effect of the III/V flux ratio to poly-type formation by photoluminescence. The cubic phase was grown under a stoichiometric condition of slightly Ga-rich side, with an III/V ratio of about one.

Analysis of effects of sizes of orifice and pockets on the rigidity of hydrostatic bearing using neural network predictor system

This paper presents a neural network predictor for analysing rigidity variations of hydrostatic bearing system. The designed neural network has feedforward structure with three layers . The layers are input layer, hidden layer and output layer. Two main parameter could be considered for hydrostatic bearing system. These parameters are the size of bearing pocket and the orifice dimension. Due to importancy of these parameters, it is necessary to analyse with a suitable optimisation method such as neural network. As depicted from the results, the proposed neural predictor exactly follows experimental desired results.

Evaluation of an atmospheric pressure chemical ionization interface for capillary electrophoresis–mass spectrometry

A simple and inexpensive approach to modify a commercial atmospheric pressure chemical ionization (APCI) interface was proposed for capillary electrophoresis–mass spectrometry (CE–MS). In order to accommodate lower flow rates in the range 1–10 μl/min, both sheath liquid and nebulizing gas were coaxially supplied to the nebulizer as an arrangement of pneumatically assisted electrospray interface. Since this paper focused on the primary study of the modified APCI interface, the performance of the interface was first evaluated by the direct infusion of a reserpine solution. Optimization of several APCI parameters, such as temperature of APCI vaporizer, nebulizing gas flow and APCI corona discharge current, were accomplished. The orifice dimension for the nebulizing gas flow was largely independent of the MS sensitivity when the nebulizing gas flow rate was ca. 0.4 l/min. A successful CE–APCI–MS separation is obtained using the modified APCI interface.

Obstruction of inferior vena caval orifice by giant left atrium in patients with mitral stenosis. A Doppler echocardiographic study from the right parasternal approach.

To examine whether an extremely enlarged left atrium (giant left atrium) obstructs the venous return from the inferior vena cava (IVC), the velocity of IVC flow was measured at its junction with the right atrium (IVC orifice) in patients with mitral stenosis by use of color and pulsed-wave Doppler echocardiography from a right parasternal longitudinal plane. The maximum dimension of the IVC orifice by two-dimensional echocardiography and the maximum IVC orifice flow velocity by pulsed-wave Doppler echocardiography were measured in 74 patients with mitral stenosis and atrial fibrillation (mean age, 59 years). The control population consisted of 16 subjects with atrial fibrillation alone (mean age, 61 years). Flow velocities in the superior vena cava and hepatic vein were also obtained by pulsed-wave Doppler echocardiography from the supraclavicular and subcostal views, respectively. Fifty-one mitral stenosis patients without severe tricuspid regurgitation were divided into two groups according to the left atrial dimension (LAD), which was measured by the standard left parasternal long-axis view (group A: n = 33, LAD less than 65 mm; group B: n = 18, LAD greater than or equal to 65 mm). Peak inspiratory and expiratory velocities of IVC orifice flow in diastole averaged over three consecutive inspirations in group B (mean +/- SD, 93.4 +/- 32.0 and 47.6 +/- 19.8 cm/sec) were significantly greater (p less than 0.01) than in the control subjects (67.9 +/- 12.8 and 34.5 +/- 7.0 cm/sec) and in group A (70.2 +/- 18.4 and 38.1 +/- 11.5 cm/sec, respectively). However, there were no significant differences in superior vena caval and hepatic vein flow velocities among the three groups. The maximum IVC orifice dimension in group B (11.4 +/- 4.4 mm) was significantly smaller than in the control subjects (20.1 +/- 2.1 mm) and in group A (18.6 +/- 5.4 mm) because of displacement of the atrial septum into the right atrium. There were significant negative correlations between the IVC orifice dimension and the peak IVC orifice flow velocity (r = -0.62, SEE = 0.33 cm/sec, n = 67, y = e(-0.01x + 3.6), p less than 0.01) as well as the left atrial dimension (r = -0.71, SEE = 0.32 mm, n = 67, y = e(-0.02x + 3.8), p less than 0.01) in these 51 patients and control subjects. In the remaining 23 patients with severe tricuspid regurgitation, the peak inspiratory IVC orifice velocity (n = 9, 88.6 +/- 30.0 cm/sec) was significantly greater (p less than 0.05) and the IVC orifice dimension (23.8 +/- 9.7 mm) significantly smaller (p less than 0.05) in patients with a giant left atrium than in those without (n = 14, 69.9 +/- 15.3 cm/sec and 30.5 +/- 9.6 mm, respectively); in the latter, the IVC orifice dimension was significantly (p less than 0.05) greater than in the controls. A giant left atrium in patients with mitral stenosis obstructs venous return at the IVC orifice by marked displacement of the atrial septum toward the right atrium.

Doppler and echocardiographic features of normal and dysfunctioning bioprosthetic valves

Echocardiographic and Doppler studies were performed on 183 clinically normal and 58 severely dysfunctioning bioprosthetic mitral, aortic and tricuspid valves. The valve dysfunction resulted from spontaneous cusp degeneration in 49 instances and from paravalvular regurgitation in 9. The pulsed Doppler study demonstrated regurgitant flow in 36 (92%) of 39 regurgitant valves and 8 (90%) of 9 paravalvular regurgitant valves. Diagnostic echocardiographic features were present in only 51 and 10% of the patients, respectively. Although the Doppler regurgitant jet was peripheral in seven of the nine patients with paravalvular regurgitation, it was not possible to differentiate these patients from those who had valve degeneration and cusp tear at the periphery of the valve ring. Eight patients presented with a musical holosystolic murmur of mitral insufficiency. In all eight there was a characteristic honking intonation on the audio signal and a striated shuddering appearance on the video Doppler signal. Ten stenotic mitral bioprosthetic valves (less than or equal to 1.1 cm2 valve orifice) were identified by Doppler study. Diagnostic echocardiographic features were present in only two of these patients. The Doppler-derived valve orifice dimension correlated well (r = 0.83) with cardiac catheterization values. Fourteen asymptomatic or minimally symptomatic patients had echocardiographically thickened mitral cusps (greater than or equal to 3 mm). These patients had a significantly (p less than 0.0001) smaller valve area as compared with normal control valves, and during 4 to 24 months of follow-up, five of these patients developed severe valve regurgitation or stenosis. Doppler ultrasound is more sensitive than echocardiography in diagnosing bioprosthetic valve stenosis and regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)