Fluid Height Research Articles

Outer nuclear layer recovery as a predictor of visual prognosis in type 1 choroidal neovascularization of neovascular age-related macular degeneration

To investigate the changes in outer nuclear layer (ONL) thickness during anti-vascular endothelial growth factor (VEGF) treatment in type 1 choroidal neovascularization (CNV) and its impact on vision. Type 1 CNV eyes (n = 94) were retrospectively compared to normal control eyes (n = 35). Along with best-corrected visual acuity (BCVA), the location of CNV, foveal ONL thickness, and subretinal fluid height were measured using optical coherence tomography (OCT) and analyzed. Visual outcome and OCT biomarkers were compared. As a result, the CNV group had thinner foveal ONL and worse BCVA compared to the control group. ONL thickness recovered partially along with visual improvement following 3 monthly initial loading doses of aflibercept injections, and it correlated with the final BCVA during the 1-year follow-up. Eyes achieved foveal ONL recovery over + 10 µm had lower subfoveal CNV (45.5%) and showed better visual outcomes than eyes with stationary ONL or suboptimal ONL recovery (76.0%, p = 0.012). In conclusion, type 1 CNV eyes that recovered foveal ONL thickness at initial loading of anti-VEGF demonstrated good final visual outcome during the 1-year follow-up. Monitoring the foveal ONL thickness during early anti-VEGF treatment can give information about the visual outcomes in type 1 CNV.

Bilateral Choroidal Thicknesses Analysis of Active and Resolved Central Serous Chorioretinopathy

Objectives: This study aimed to examine the choroidal thicknesses (ChT) changes before and after resolution of subretinal fluid in patients with central serous chorioretinopathy (CSR) and in their fellow eyes. Materials and Methods: Patients with acute CSR were studied and followed until subretinal fluid resolved. Sixty-eight eyes from 34 CSR cases (24 men and 10 women, mean age of 37.34±6.2, range 27-50) were examined. Their ChT was measured using enhanced depth imaging optical coherence tomography (EDI-OCT). Imaging repeated after sub-retinal fluid resolution. ChT changes were analyzed before and after the resolution of subretinal fluid in both eyes. Results: Mean ChTs in CSR eyes were 387±97 µm, 414±97 µm, and 384±87 µm in 1 mm temporally away from the center, central sub-fovea, and 1 mm nasally away from the center, respectively; and those in the fellow eyes were 283±55 µm, 303±60 µm, and 282±56 µm in the same order. ChT decreased significantly (P≤0.001) to 305±82 µm, 334±86 µm, and 313±76 µm in CSR eyes and to 242±52 µm, 262±55 µm, and 246±48 µm in contralateral eyes in the temporal, central sub-foveal, and nasal sequences after subretinal fluid resolution, respectively. There was a strong correlation between the ChT in active phase and the ChT in resolved phase in both affected and fellow eyes. There was no detectable correlation between central sub-foveal fluid height and sub-foveal choroidal thickness in the affected and fellow eye (P=0.23). Conclusion: Nasal and temporal comparison of the affected and fellow eyes before and after fluid resolution showed that the nasal choroid was thinner than temporal choroid (as the average population) in active phase. In the resolution phase, however, it was the temporal choroid that was thinner than the nasal choroid, and the resolution pattern was not asymmetric.

Changes of microstructure of central serous chorioretinopathy on OCT and its relationship with prognosis

PurposeTo quantitatively evaluate the relationship between retinal microstructure and prognosis in patients with central serous chorioretinopathy(CSC) using optical coherence tomography(OCT). MethodsThree hundred and ninty-eight affected eyes of patients with central serous chorioretinopathy were included in this retrospective study. The OCT images of all patients were analyzed in baseline, and logistic regression analysis were performed with 11 independent variables, and subretinal fluid absorption in 3 months after therapy as dependent variable. The correlation between shortage of ellipsoid baseline and height of foveal subretinal fluid, width of foveal subretinal fluid were analyzed respectively. The difference of duration and baseline logMAR visual acuity in eyes with and without double layer sign or subretinal hyper-reflective materials were analyzed respectively. The difference of therapeutic outcome among different therapeutic methods was also analyzed in eyes with double-layer sign and subretinal hyper-reflective materials respectively. ResultsIn the regression analysis with subretinal fluid absorption in 3 months after therapy as dependent variable, disintegrity of ellipsoid zone was statistically significant(P<0.0001,B=1.288). There is no correlation between disintegrity of the ellipsoid zone and the width or height of subretinal fluid. The duration of disease in eyes with double layer sign or subretinal hyper-reflective materials was longer than those without these features(P<0.001, P<0.0001). In the eyes with the double-layer sign or subretinal hyper-reflective material, the difference of logMAR visual acuity 3 months after treatment between 2 therapeutic methods was not statistically significant. ConclusionsUsing optical coherence tomography to evaluate microstructure changes in eyes with central serous chorioretinopathy quantitatively, we found that subretinal fluid was easier to absorb completely in eyes with less disintegrity of ellipsoid zone. Double layer sign and subretinal hyper-reflective materials are more common in eyes with longer duration of disease.

Anatomical and functional impact of verteporfin shortage in patients with chronic central serous chorioretinopathy

BackgroundTo describe the functional and anatomical impact that the worldwide shortage of verteporfin has had on patients diagnosed with chronic central serous chorioretinopathy (cCSCR) whose treatment with photodynamic therapy (PDT) had to be delayed. MethodsProspective observational study. Patients were divided into two groups based on the time interval since PDT had been indicated: groups 1 and 2, with waiting times of less and more than 9 months respectively. Best corrected visual acuity (BCVA), the maximum height of the subretinal fluid (MSRF) and subfoveal choroidal thickness (SFCT) at the baseline visit and the last visit were compared. Results49 eyes of 48 patients with cCSCR were included. The mean waiting time for PDT was 9.0 ±3.8 months. The mean BCVA was 69.0 ±17.1 letters and 68.9 ±16.4 letters for the baseline and last visit respectively, showing no difference (p= 0.958). Although there was no difference in the mean global BCVA, 15 eyes (30.5%) showed a deterioration of ≥5 letters, including 7 eyes (14%) with a decrease of ≥10 letters. Mean MSRF height was 151.4 ±97.2 μm and 98.2 ±83.1 μm for the baseline and last visit respectively (p= 0.005), persisting in 74.5% of the eyes. ConclusionNo significant impact was observed in the BCVA in cCSCR due to the shortage of verteporfin. However, one-third of patients had BCVA loss. There was a significant spontaneous decrease in MSRF, but it persisted in the majority of the patients, still susceptible to PDT.

Electrophysiological and anatomical outcomes of subthreshold micropulse laser therapy in chronic central serous chorioretinopathy.

To evaluate short-term efficacy of subthreshold micropulse laser therapy on chronic central serous chorioretinopathy (CSC) electrophysiologically and anatomically. This prospective study included 18 eyes with chronic CSC. Subthreshold micropulse laser therapy was applied to the eyes using Endpoint Management System (EpM). The efficacy of the treatment was evaluated with optical coherence tomography (OCT) and multifocal electroretinography (mfERG) measurements before and after one month of the treatment. The mean patient age was 47.3±5.7 years (ranged between 36 and 56). The mean symptomatic time of the disease was 12.7±3.33 months. Central macular thickness, choroidal thickness, subretinal fluid height and width showed statistically significant decreases after EpM treatment (p<0.05). P 1 amplitude of ring 1, 3, 4, and 5 in mfERG increased significantly (p< 0.05). The study demonstrated that, in both OCT and electrophysiological evaluations, EpM subthreshold laser therapy resulted in anatomical and functional improvements in chronic CSC.

Hydrodynamics performance of Newtonian and shear-thinning fluids in a tank stirred with a high shear impeller: Effect of liquid height and off-bottom clearance

The hydrodynamics performance of a ring-style Hockmeyer© high-shear impeller (HSI) in an unbaffled tank with Newtonian and shear-thinning fluids at Reynolds numbers (Re) between 20 and 300 is addressed. Power measurements of this study were used to validate computational fluid dynamics simulations. Key hydrodynamic parameters for the HSIs performance, i.e., pumping and power numbers, and viscous dissipation are analyzed. The effect of the off-bottom clearance (C), working fluid height (Z) (in the range 0.18 ≤C/T ≤ 0.38 and 0.8 ≤Z/T ≤ 1, where T is the tank diameter), and fluid rheology, on these parameters were investigated. Results show that the examined C/T and Z/T ratios do not significantly affect the power number. The fluid rheology, C/T and Z/T had, on the contrary, a significant impact on the remaining hydrodynamic parameters. For 45 ≤Re≤ 300, the shear-thinning fluid showed better performance for dispersion processes, i.e., higher pumping number and viscous dissipation, and lower power number than the Newtonian fluid.

The porous medium equation as a singular limit of the thin film Muskat problem

The singular limit of the thin film Muskat problem is performed when the density (and possibly the viscosity) of the lighter fluid vanishes and the porous medium equation is identified as the limit problem. In particular, the height of the denser fluid is shown to converge towards the solution to the porous medium equation and an explicit rate for this convergence is provided in space dimension d ⩽ 4. Moreover, the limit of the height of the lighter fluid is determined in a certain regime and is given by the corresponding initial condition.

Convective-Wave Solutions of the Richard–Gavrilyuk Model for Inclined Shallow-Water Flow

We study for the Richard–Gavrilyuk model of inclined shallow-water flow, an extension of the classical Saint Venant equations incorporating vorticity, the new feature of convective-wave solutions analogous to contact discontinuities in inviscid conservation laws. These are traveling waves for which fluid velocity is constant and equal to the speed of propagation of the wave, but fluid height and/or enstrophy (thus vorticity) varies. Together with hydraulic shocks, they play an important role in the structure of Riemann solutions.

Control Volume Analysis of the Infusion Rate in Cephalic and Median Cubital Veins Based on Infusion Bag Height and Peripheral Venous Catheter Inner Diameter: Application of Bernoulli's Equation and Consideration of Frictional Forces.

This pilot study aimed to provide basic data on intravenous infusion nursing by analyzing the infusion rate in the cephalic and median cubital veins depending on the height of the infusion bag and inner diameter of the peripheral venous catheter (PVC). While infusing 0.9% normal saline at 22 °C (room temperature) into elbow cephalic and median cubital veins, the infusion rate may be controlled by adjusting the fluid height and PVC diameter. To assess the validity of the laminar flow assumption, the study estimated the Reynolds number (Re) using the velocity obtained by applying Bernoulli's equation considering the friction coefficient. At a constant fluid height, the infusion rate increased with increasing PVC diameter. At a constant PVC diameter, the infusion rate increased with increasing fluid height. In a comparison between the cephalic and median cubital veins at constant fluid height and PVC diameter, the solution was infused at a higher rate into the cephalic vein, which was under lower venous pressure. The analysis of the infusion rate according to fluid height and PVC diameter provided basic data on intravenous infusion nursing. The results are expected to provide evidence for the standardization of intravenous infusion nursing.

Non-intrusive diagnostics of differentially-heated two-component immiscible fluid layer with phase change

Experiments on buoyancy-driven convective phenomena in a differentially-heated two component immiscible fluid layer with phase change phenomena have been reported. The real-time mapping of the transients associated with the process has been affected in a complete non-intrusive manner using rainbow schlieren deflectometry. Experiments have been performed for varying heat flux levels supplied to the lower horizontal surface of the cavity and for different heights of the secondary fluid layer. The two-component immiscible fluid mixture comprises of water as the (lighter) primary fluid layer and dichloromethane (DCM) as the (heavier) secondary fluid component. The supplied heat flux levels are sufficient enough to induce phase change in the secondary fluid layer through nucleate pool boiling. In addition to the real-time mapping of the buoyancy-induced convection in both the fluid layers, the process of vapor bubble inception, their growth and departure from the lower heated wall of the cavity have been recorded in the form of time-lapsed schlieren images. Conditions under which the continued interaction of the vapor phase of DCM with the interface leads to interface deformation and its final breakage have been investigated. Based on the force balance analysis, the critical volume of the DCM vapor phase required for interface breakage has been determined. Dependence of parameters such as neck breakage height, time required for interface breakage etc. on the supplied heat flux level and height of the secondary fluid has been investigated. The experimental observations revealed the importance of vapor bubbles-induced fluid agitation in the otherwise stagnant primary fluid layer, disruption of the thermal boundary layer in a completely passive manner as the upward rising vapor volume condenses at the top horizontal surface of the differentially-heated cavity and their implications in possible heat transfer enhancement.

Size-dependent linear and nonlinear vibration of functionally graded CNT reinforced imperfect microplates submerged in fluid medium

The linear and nonlinear vibrations of functionally graded carbon nanotubes reinforced microplate (FGCNTRM) submerged in fluid medium have been studied analytically. The primary novelty of this research is to take into consideration the effects of using carbon nanotubes (CNT) and geometric imperfection on the vibrational behavior of microplates submerged in the fluid. Equations of motion are obtained by first-order shear deformation theory of plates and considering the size effects and large deformations. Effective mechanical properties have been determined using the rule of mixtures for four various types of CNT distributions. The nonlinear equations of motion are discretized using the Galerkin method, and the equation response is acquired applying the method of multiple time scales. After verifying the results, the effect of microplate geometric characteristics, small size parameter, fluid height, geometrical imperfection amplitude, weight fraction, and distribution of CNT on linear and nonlinear frequencies as well as amplitude-frequency curves have been studied. The results demonstrate that an increase in fluid height leads to a decrease in the natural frequency. Also, geometric imperfection causes the stiffening behavior of the softening spring and substantially bends the response curve to the right. This bending can induce jump instabilities as the frequency slowly varies.

Dynamic analysis of a partially-filled cylindrical–conical–cylindrical shell representing a pressure vessel

A base-supported partially-filled fluid–shell system representing the pressure vessel of a fast reactor is studied. The shell is made of two cylindrical parts joined through a conical part. The shell is characterized using Donnell’s theory, while the fluid is modeled using a velocity potential approach. Compatibility and interface conditions led to the energy functional, minimization of which yielded natural frequencies. The approach was validated against previously studied joined systems. Parametric studies revealed that vibration frequencies of the fluid-shell system (i.e., bulging frequencies) are comparable to shell-only vibration frequencies if only the lowermost part is filled. Vibration frequencies of the free fluid surface (i.e., sloshing frequencies) do not change materially with fluid height if most of the vessel is filled. Present study did not consider the coupling between bulging and sloshing modes, which may need to be considered for a completely-filled vessel with a large base radius (e.g., > 3 m) as the two sets of frequencies for such systems can be comparable.

Finite element analysis on tunable solid/fluid phononic crystal for surface acoustic wave bandgaps with various fluid heights

In this study, the propagations of surface acoustic waves (SAWs) in two-dimensional solid/fluid phononic crystal (PC) structures were investigated. The PC structures are composed of a periodic sequence of hollow pillars deposited on a semi-infinite substrate, which can be filled with various kinds/heights of fluid. Finite element analysis was used to study the characteristics of SAW bandgaps for the unit cell of PCs. The results showed that the distribution of bandgaps varies with the fluid height. Additionally, the change of bandgaps is more sensitive to mercury than water. Furthermore, transmission properties of SAWs for the PCs filled with different mercury heights are analyzed. It can be found that the PCs can inhibit the propagation of SAWs with a frequency corresponding to the bandgaps validly. Meanwhile, comparing with the transmission spectra, it could be concluded that the transmission troughs shift to lower frequency overall as the mercury heights increase. The results obtained in this study are instructive and meaningful for the practical design of tunable SAW PCs.

Physical simulation technologies and testing system for cavern shape control from single-well solution mining in rock salt.

The shape of the salt cavern is very important for the safe operation of gas storage facilities in rock salt. A physical simulation test is an effective means to study the shape control of salt caverns. To accurately simulate the process and parameters of single-well solution mining in rock salt, we developed simulation technologies and a testing system for cavern shape control. Based on the flow similarity principle, we established a sealing technology for dynamic-static disturbance and successfully replicated the solution mining process for forward and reverse circulations. Based on the requirement of protective fluid in the field, we developed a protection liquid unit to control the oil pad height to avoid overdissolution or uneven dissolution at the top of the salt cavern. From the principle of distance determination by laser and video, we developed a salt cavern shape visualization and micro-distance detection system that can realize the size measurement and real-time visualization of the salt cavern in pressurized corrosive environment. We put forward the control technology of the testing system that can achieve the integrated and collaborative control of inner and outer pipe spacing, water flow during injection-production circulations, and the height of protection fluid. Finally, we carried out a physical simulation test of solution mining for cavern shape control. The shape and size of the salt cavern from the test are in good agreement with the design. This study can provide an important basis for determining the optimal solution in mining technology and the parameters for cavern shape control.

On simple models for gravity currents from moving sources

The propagation of the gravity current generated from a moving source of buoyancy is of interest in deep-sea mining and related technologies. The study by Ouillon et al. (J. Fluid Mech., vol. 924, 2021, A43) elucidated some salient patterns of the flow concerning a source close to the bottom on the basis of direct numerical simulation on a supercomputer. Here, we present a simple box model that provides further insights and useful analytical approximations for this gravity-current flow system. We show that this flow is very different from that produced by a moving source at the top, studied by Hogg et al. (J. Fluid Mech., vol. 539, 2005, pp. 349–385). The model confirms that the main governing parameter is the ratio $a$ of speed of source to that of buoyancy propagation. The model points out dependency also on the front-jump Froude number (which implies dependency on the height of the ambient fluid). For a sufficiently large $a &gt;a_{crit}$ , a supercritical regime appears in which the gravity current forms a wedge behind the moving source; in the subcritical regime, the upstream propagation attains a maximum $x_m$ at time $t_m$ . The model predicts the value $a_{crit}$ , the distance and time $x_m$ and $t_m$ in the subcritical case, and the shape of the wedge in the supercritical case, without any adjustable constant. Comparisons with the numerical data show fair agreement.

The Efficacy of Anti-VEGF Therapy for Putative or Visible CNV in Central Serous Chorioretinopathy by Optical Coherence Tomography Angiography.

Purpose To investigate the effect and underlying mechanism of intravitreal antivascular endothelial growth factor (VEGF) in patients with putative or visible choroidal neovascularization (CNV) secondary to central serous chorioretinopathy (CSCR) with optical coherence tomography angiography (OCTA). Methods In a retrospective cohort study, 16 eyes of 15 treatment-naïve CSCR patients were included and divided into two groups: a putative CNV group with nonhomogenous hyperreflectivity in the slab of choriocapillaris and a visible CNV group with obvious tangled vascular network in the slab of choriocapillaris in OCTA. Patients were recorded with best-corrected visual acuity (BCVA). The parameters, evaluated by OCTA, included central macular thickness (CMT), the height of subretinal fluid (SRF), the number of hyperreflective foci (HRF), and the area of putative or visible CNV. Results Compared with the baseline, visual acuity was improved significantly at the last follow-up, and CMT and the height of SRF were decreased significantly (P < 0.0001). The number of HRF was also declined in the outer retina and the choriocapillaris layer (P=0.0343). Although the visible CNV area in the eyes represented virtually unchanged during anti-VEGF treatment (P=0.4015), the area of putative CNV displayed an obvious reduction (P=0.0081). Conclusion Anti-VEGF is effective in treating CSCR coexisting putative or visible CNV. Early initiation of anti-VEGF therapy benefits CSCR patients with putative CNV detected by OCTA. Translational relevance nonhomogenous hyperreflectivity in the choriocapillaris layer in OCTA indicates putative CNV in patients with CSCR, implying early treatment with anti-VEGF.

Free vibration analysis of an auxetic honeycomb sandwich plate placed at the wall of a fluid tank

This paper presents a parametric investigation of the free vibration characteristics of an auxetic honeycomb sandwich plate mounted at the wall of a liquid tank. Frostig's second model is utilized in the core, while first-order shear deformation theory (FSDT) is applied to the face sheets. The honeycomb core is homogenized using one of the newest revised models (Tornabene's model), and the fluid is assumed to be ideal. The governing equations of motion are derived using Hamilton's principle and solved using the Galerkin method. Present solution method, honeycomb core homogenization formula, and mathematical framework for the fluid-sandwich plate interaction are verified using 3D Finite Element Analysis (FEA). Finally, the wet fundamental frequency is investigated with geometric parameters such as the ratio of tank dimensions to the plate length, fluid height from the plate's bottom edge, plate location at the tank wall, and honeycomb cell geometry. According to the results of this study, the thickness of the face sheet and the cell wall enhance the wet fundamental frequency, while the cell aspect ratio decreases it.

Importance of subfoveal fluid height on visual outcome in macula-off retinal detachments

AimsTo investigate the effect of subfoveal fluid height (SFFH) on visual outcome after macula-off retinal detachment (RD) repair.MethodsProspective interventional case series of consecutive patients undergoing pars plana vitrectomy with gas...

An experimental investigation of slat-screens to mitigate fluid sloshing in microgravity

The new age of space exploration has brought forth growing implications of space debris connected to satellites, and as such on-orbit satellite refuelling is an area of active research. To refuel a satellite on-orbit, a servicing satellite transfers propellant to the empty fuel tank of the satellite being serviced. A significant impediment to such a practice is the development of fluid sloshing motion during this process. This paper presents a study of the use of slat screens to damp fluid sloshing motion during a simulated refuelling of a fuel tank under microgravity conditions. There is particular interest in the sloshing motion developed due to internal forces produced from fluid injection. Two fluids, each analogous to common spacecraft propellants; hydrazine and liquid oxygen (LOX), were tested under a microgravity environment created by parabolic manoeuvres aboard the National Research Council of Canada's (NRC) Falcon 20 research aircraft. The experimental setup included three test chambers, two of which contained a perforated and a single-entry slat screen, designed to mitigate sloshing. High-speed imaging of fluid sloshing development within the test chambers was captured and analysed. The rate of fuelling was varied during subsequent parabolas to 25%, 50% and 75% of the internal volume capacity (1 L). Based on initial findings, statistical differences exist (P<0.05) in the latency for the LOX analogue, to reach 75% and 95% of the total chamber height. Differences were observed specifically between the control chamber and the chamber with perforated slat screens. Furthermore, qualitative observations of the hydrazine analogue fluid motion in microgravity show that at 50% fill ratio, slat screens result in a plateau of maximum fluid height. This suggests that slat screens may be an effective method of damping fluid sloshing motion and could be adopted by industry in the pursuit of on-orbit refuelling and the development of more sustainable spacecraft.

Effect of High Myopia on Delayed Absorption of Subretinal Fluid after Scleral Buckling Surgery.

This study compared the absorption of subretinal fluid (SRF) in patients with rhegmatogenous retinal detachment (RRD) with and without high myopia after scleral buckling (SB) and investigated the effect of high myopia on SRF absorption. This retrospective study included patients with primary macula-off RRD grouped according to myopia and age. The optical coherence tomography (OCT) and OCT angiography indicators included subretinal fluid height (SRFH), subfoveal choroidal thickness (SFCT), and choroidal capillary blood flow density (CCFD) measured regularly. The presence of SRF 3 months after surgery was defined as delayed absorption. Overall, 90 eyes of 89 patients were enrolled, and 46 eyes (51.11%) had high myopia. In 43 eyes (47.78%), SRF absorption was delayed. There was no significant difference in SRF absorption after SB between the high and non-high myopia groups; younger patients (<35 years) had a higher probability of delayed absorption (p < 0.05). The SFCT in high myopia was significantly thinner than that in the non-high myopia group (p < 0.05); SFCT and SRFH were positively correlated (rs = 0.275, p = 0.002), and there was a significant difference between the average CCFD with and without SRF (p < 0.05). High myopia had no significant effect on SRF absorption after SB.