Velocity Flow Research Articles

Dobutamine 3D strain in the left anterior descending subtended ventricular territory: evidence for relationship with the respective velocity flow reserve

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Three dimensional speckle tracking imaging (3DST), provides an evolving means to interrogate left ventricular (LV) function. However, its clinical application still remains limited. Purpose Purpose of the study was to interrogate the relationship between regional deformation by 3DST in left anterior descending artery (LAD) subtended territory and the respective coronary flow reserve (CFR). Methods Fifty patients aged 63 ± 6 years with chronic coronary syndromes were studied. Patients had no evidence of dobutamine (DOB) induced ischemia in LAD territory. Distal LAD CFR was estimated by adenosine Doppler echo (140mg/kg/min). 3DST derived integral strain (IS) and respective components (longitudinal -LS, circumferential –CS, radial -RS) were estimated by a full volume sweep (3.5 MHz sector probe) at >20 volumes/sec. A 16 LV sectors (sc) polar map was provided (Artida,Toshiba) with 10/16 sectors (sc) analysed, 6 sc being the conventional LAD territory (sc: 3,4,5,6,7,8) and another 4 sc being adjacent ones (sc: 1, 2, 9, 10). 3D datasets acquired at rest (R) and low dose DOB (20mg/kg/min). LV mass was automatically measured from volumetric data sets and its variability during cardiac cycle was considered as an index of coherence for true LV borders recognition. Results CFR was >2 in all pts (range 2.0-4.2, 2.74 + 0.46). Mean variability of LV mass between R and DOB was 0.044 (range: -0.090-0.008, p = ns). 3DST strain was related with LAD CFR as follows: 1.For IS: at R: sc1: r = 0.38, p = 0.023, sc3: r = 0.44, p = 0.006, sc5: r = 0.35, p = 0.03, sc9: r = 0.50, p = 0.002. At DOB sc7: r = 0.31, p = 0.05. 2.For LS: at R: sc5: r=-0.40, p = 0.01. 3.For CS: at R: sc5: r=-0.33, p = 0.02, sc5: r=-0.46, p = 0.004. 4.For RS: at R: sc9: r=-0.38, p = 0.08. The % changes of regional IS post DOB compared to R were also related with CFR LAD in the sectors sc1 and sc3 (r = 0.34, p = 0.05, and p = 0.40, p = 0.002 respectively). Conclusion 3DST derived LV deformation indices in the LAD territory are related with the respective CFR. LV regional integral strain has a stronger relationship with LAD CFR when compared to the partial vectors. The 3DST derived deformation indices seem sensitive enough to reproduce the flow function relationship in the LAD territory. Thus, potential applicability has to be supported.

On fluid flow regime transition in rough rock fractures: Insights from experiment and fluid dynamic computation

The influence of roughness, aperture and asperity irregularity on fluid flow regimes in rough rock fractures was investigated by performing coupled triaxial water flow tests and fluid dynamic computation. Ten sets of fabricated curved wedges were developed to obtain different fracture surface roughness by splitting under compression. Three fluid flow regimes were identified in mated rock fractures: pre-linear flow at low flow velocity, linear Darcy’s flow at the medium flow velocity and post-linear flow at high flow velocity. In pre-linear flow regime, the increasing rate of flow rate increased with water pressure gradient, but it decreased in post-linear flow regime. The pre-linear flow is ascribed to the slippage effect of water-fracture interfaces, while the post-linear flow is mainly due to inertial effects. The critical hydraulic gradient for fluid flow regime transition from pre-linear to linear flow increased with the increase of confining stress. The numerical modeling shows that the asperity irregularity influences the flow regime. For low-speed flow in fracture under slip boundary condition, the slip flux per unit width in the fracture with triangular asperity is largest, while that of rectangular asperity is smallest. For high-speed flow in fracture with non-slip boundary condition, the rectangular asperity element causes more severe nonlinearity when compared to the fractures of trapezoidal and triangular asperity elements.

Whole-brain mapping of mouse CSF flow via HEAP-METRIC phase-contrast MRI.

PurposeCSF plays important roles in clearing brain waste and homeostasis. However, mapping whole‐brain CSF flow in the rodents is difficult, primarily due to its assumed very low velocity. Therefore, we aimed to develop a novel phase‐contrast MRI method to map whole‐brain CSF flow in the mouse brain.MethodsA novel generalized Hadamard encoding–based multi‐band scheme (dubbed HEAP‐METRIC, Hadamard Encoding APproach of Multi‐band Excitation for short TR Imaging aCcelerating) using complex Hadamard matrix was developed and incorporated into conventional phase contrast (PC)‐MRI to significantly increase SNR.ResultsSlow flow phantom imaging validated HEAP‐METRIC PC‐MRI’s ability to achieve fast and accurate mapping of slow flow velocities (~102 µm/s). With the SNR gain afforded by HEAP‐METRIC scheme, high‐resolution (0.08 × 0.08 mm in‐plane resolution and 36 0.4 mm slices) PC‐MRI was completed in 21 min for whole‐brain CSF flow mapping in the mouse. Using this novel method, we provide the first report of whole‐brain CSF flow in the awake mouse brain with an average flow velocity of ~200 µm/s. Furthermore, HEAP‐METRIC PC‐MRI revealed CSF flow was reduced by isoflurane anesthesia, accompanied by reduction of glymphatic function as measured by dynamic contrast‐enhanced MRI.ConclusionWe developed and validated a generalized HEAP‐METRIC PC‐MRI for mapping low velocity flow. With this method, we have achieved the first whole‐brain mapping of awake mouse CSF flow and have further revealed that anesthesia reduces CSF flow velocity.

Practical analysis of cleaning water supply pipeline using air and water flushing technology

To ensure the safety of water quality, pipe network cleaning and security management are put forward higher requirements. Traditional single-phase water flushing pipe technology requires high velocity and large flow rate of water, which does not suitable for large-diameter pipes. Air and water flushing pipes are new pipeline cleaning technology, which has high efficiency, good washing effect, and can save a lot of water. The principles of airwater flushing large-diameter, large-deviation-elevation, and many- ups-and-downs pipes are described in this paper. Based on the two-phase flow theories, it analyzes complex hydraulic characteristics and control parameters for flushing pipeline. Combine with engineering practice, air and water flushing diameter of 800 mm pipeline in Shanghai city and flushing pipe parameters are introduced. The air and water flushing effect and water resource consumption reduction are analyzed, as well.

Three-Dimensional Analysis of the Influence of the Magnetic Flux Density on Minimum PR in a Faraday-Type MHD Channel

The magnetohydrodynamic (MHD) behavior and performance characteristic have been revealed by 3-D numerical simulation of the Faraday-type MHD generator. Numerical results show that the generator inlet–outlet pressure ratio (PR) will affect the plasma behaviors and generator performance in the channel. At high PR, the plasma flows at supersonic, and higher electric power [enthalpy extraction rate (EE)] can be obtained. However, at low PR, boundary layer separation occurs with deflected flow of velocity streamlines and vortex in the separated flow region, owing to the oblique shock wave. Therefore, there exists a minimum PR to maximize power generation performance. Under the strong MHD interaction, the Lorentz force causes the loss of Mach number and the increase of static pressure, but it can alleviate the effect of oblique shock for a lower PR. Furthermore, suppressing the boundary layer separation effect gradually evolves into a normal shock wave. When PR is higher, the thermoelectric conversion efficiency increases, and then a weak shock wave will be generated in the channel, which will propagate upstream and evolve into a normal shock wave. Consequently, under a higher magnetic flux density, the minimum PR can be effectively reduced, and the best generator performance can be obtained. In addition, an “ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$M$ </tex-math></inline-formula> ”-shaped velocity profile will be generated due to the significantly increased MHD interaction. The results calculated in the present simulation are valuable and important for setting working gas conditions and evaluating generator performance.

Innovation of vortex finder geometry (tapered in-cylinder out) and additional cooling of body cyclone on velocity flow field, performance, and heat transfer of cyclone separator

This paper studies numerical analysis about the effect of the vortex finder (Tapered in-Cylinder out) geometric innovation in a cyclone separator. Four variations of the length of the vortex finder 0.5 Dc, 0.75 Dc, Dc, and 1.25 Dc will be simulated under cooling and without cooling conditions on the velocity flow field, cyclone performance, temperature distribution, and heat transfer. The RSM turbulence model is used to simulate fluid flow. The Eulerian-Lagrangian approach was chosen to predict the phase movement of the particles. The trajectories of particles in the flow are tracked individually using the DPM method. The cooling model is applied assuming a constant temperature on the surface of the cyclone body. The simulation results show similar trends both with experimental studies and numerical simulations. The application of additional cooling to the cyclone, reduced the pressure drop up to 13%. The cyclone collection efficiency showed a non-significant increase but most of the particles collected were drier due to the increasing heat transfer 15–25% in any cases of variation.

Simulation Study of Rice Cleaning Based on DEM-CFD Coupling Method

In mechanized rice harvesting, the performance of the cleaning device is one of the important factors that affect the overall efficiency of the combine-harvester. To study the influence of different parameters on the cleaning efficiency, the influence of airflow velocity and the inclination angle on the cleaning effect was analyzed. Both simulation and experimental results prove that the increase of airflow velocity and the inclination angle will reduce the impurity rate of rice and increase the entrainment loss rate. The addition of a vibrating sieve to the device reduces the trash rate of rice, but the entrained loss rate increases accordingly. After tilting the sieve surface by 10°, a reduction in both the impurity rate and the entrainment loss rate of rice was found in combination with the force analysis of the particles on the sieve surface. The effect of the device structure on the internal flow field distribution was analyzed by comparing the eddy viscosity and velocity flow lines inside the three scavenging device structures. Simulation after calibration of rice moisture content revealed that humid rice cleaning was not effective.

Influence of the spark plug mounting angle on spark ignition process at different flow velocities

Influences of the spark-plug mounting angle on the spark ignition of gasoline-air mixtures in high velocity flows were investigated in a combustion chamber connected at the end of a rapid compression machine. Gasoline-air mixture with an air excess ratio of 1.9 was combusted. A spark plug was mounted on the combustor wall at angles of −30°, −15°, 0°, 15°, and 30°. Flow velocity at the spark plug was varied from 5 to 20 m/s by adjusting the driving pressure of the piston. Time resolved spark-discharge voltage and current were measured with a voltage and a current probe, and the discharge energy was calculated using them. Behaviors of the discharge channel were observed optically with a high-speed video camera in addition to simultaneous measurements of OH* chemiluminescence from the flame kernel with the other high-speed video camera. The results showed that the averaged induction time of flame kernel initiation increased monotonously with an increase in the plug mounting angle from −30° to 30° in flows with velocities of 5 and 10 m/s. However, the increasing trend became less obvious with velocities of 15 and 20 m/s, involving with larger variation in induction time. Discharge duration became shorter with an increase in the plug mounting angle regardless of the same setup. Negative mounting angle resulted in frequent short-circuits/restrikes at the early phase. On the other hand, positive mounting angles resulted in a longer discharge channel length, higher energy deposition before the first restrike and longer induction time of the first restrike. Although the discharge channel at positive mounting angles elongates along with the flow, the early flame kernel was developed toward the center of the swirl. Thereafter, flame propagated outward from the central region, where the flow speed was lower than the downstream area. Negative mounting angle led to a more oval flame kernel shape and the propagation closer to combustion chamber wall, which showed a shorter induction time of flame kernel initiation in the cases of 5 and 10 m/s. However, fragments of the flame kernel tended to be formed due to frequent short-circuits with the velocities of 15 and 20 m/s. This resulted in the large variation of the induction time.

Ferromagnetic nematics: A macroscopic two-fluid description.

We present the macroscopic dynamic description of a ferromagnetic nematic, where the nematic part and the magnetic part can move relative to each other. The relative velocity that describes such movements can be a slowly relaxing variable. Its couplings to the nematic and the magnetic degrees of freedom are particularly interesting since the symmetry properties (behavior under spatial inversion and time reversal) of the three vectorial quantities involved are all different. As a consequence, a number of new crosscouplings involving the relative velocity exist. Some of them are discussed in more detail. First, we demonstrate that transverse temperature gradients generate transverse relative velocities and, vice versa, that transverse relative velocities give rise to temperature gradients. Second, we show that a simple shear flow in the relative velocity with the preferred direction in the shear plane can lead in a stationary situation to a tilt of the magnetization.

Clinical research of refractory ascites of cirrhosis treated with acupoint-penetrating needling technique of acupuncture and enema with tuihuang mixture

To observe the effects on liver function, portal hemodynamics, plasma nitric oxide (NO), intestinal endotoxin (ETM) and interferon γ (IFN-γ) treated with acupoint-penetrating needling technique of acupuncture and enema with tuihuang mixture in the patients with refractory ascites of cirrhosis. A total of 120 patients with refractory ascites of cirrhosis were divided randomly into an observation group and a control group, 60 cases in each one. In the control group, the routine western medicine treatment was applied in combination with enema with tuihuang mixture. In the observation group, on the base of the treatment as the control group, acupoint-penetrating needling technique of acupuncture was added, Zhongwan (CV12) penetrated toward Shuifen (CV9), CV9 toward Qihai (CV6), CV6 toward Guanyuan (CV4) and CV4 toward Zhongji (CV3) respectively. The duration of treatment was 60 days in both groups. The clinical therapeutic effect was analyzed in the patients of both groups. Before and after treatment, the changes in body mass, abdominal circumference, 24 h urine output/week, maximum depth of dark area of ascites, liver function indicators, portal vein hemodynamics, plasma NO, ETM and IFN-γ were observed in the patients of the two groups. The total effective rate was 81.03% (47/58) in the observation group, higher than 63.16% (36/57) in the control group (P<0.05). After treatment, in the self-comparison of each group, the levels of body mass, abdominal circumference, the maximum depth of the dark area of ascites, the main portal vein diameter (Dpv), maximum blood flow velocity (Vmax) and venous blood flow (Q) were all lower than those before treatment (P<0.05), 24 h urine output/week was higher than that before treatment (P<0.05), and every indicator of liver function was improved (P<0.05). After treatment, the values of body mass, abdominal circumference, the maximum depth of the dark area of ascites, Dpv, Vmax and Q in the observation group were all lower than those in the control group (P<0.05), 24 h urine output/week was higher than that in the control group (P<0.05), and the improvement in every indicator of liver function was larger than that in the control group (P<0.05). The levels of plasma NO and ETM after treatment were all lower than those before treatment in both two groups (P<0.05), and the level of IFN-γ was higher than that before treatment (P<0.05). After treatment, the levels of NO and ETM in the observation group were lower than those of the control group and the level of IFN-γ was higher than that in the control group (P<0.05). The combined therapy of acupoint-penetrating needling technique of acupuncture and enema with tuihuang mixture effectively improves the effective rate on refractory ascites of cirrhosis, which is related to the decrease of endotoxin and the improvements of portal hemodynamics and cellular immune function.

Numerical Investigation of the Effects of Aquatic Vegetation on Wind-Induced Wave and Current Characteristics in Shallow Lakes

Aquatic vegetation is one of the important parts of the shallow lake ecosystem, which has an important impact on the characteristics of wind-driven wave and current. In this article, we embed the vegetation module into the flow model TELEMAC-3D and the wave model TOMAWAC, respectively, and construct the coupling model of flow–wave–vegetation in the open source model Open TELEMAC-MASCARET. Through the verification of two sets of experimental data, it has been proven that the model can well reproduce the influence of vegetation on current and wave. Then, the model is applied to the wind-driven wave and current simulation of a typical shallow lake, Taihu Lake. The results show that the model can accurately reproduce the characteristics of wind-driven wave and current. Aquatic vegetation significantly changes the velocity, wave height, and local three-dimensional circulation flow in the vegetation patches. At the same time, the existence of aquatic vegetation reduces the material exchange rate between the vegetation area and the outside world, which has a significant impact on the material transport characteristics of the lake. Sensitivity analysis shows that the influence of aquatic vegetation should not be ignored in the simulation of wind-induced wave current and material transport in shallow lakes.

Flow dynamics of surgical and transcatheter aortic valves: Past to present

ObjectiveTo perform an in vitro characterization of surgical aortic valves (SAVs) and transcatheter aortic valves (TAVs) to highlight the development of the flow dynamics depending on the type of valve implanted and assess the basic differences in the light of flow turbulence and its effect on blood damage likelihood and hemodynamic parameters that shed light on valve performance. MethodsA Starr–Edwards ball and cage valve of internal diameter 22 mm, a 23-mm Medtronic Hancock II SAV, a 23-mm St Jude Trifecta SAV, a 23-mm St Jude SJM (mechanical valve) SAV, a 26-mm Medtronic Evolut TAV, and a 26-mm Edwards SAPIEN 3 TAV were assessed in a pulse duplicator under physiological conditions. Particle image velocimetry was performed for each valve. Pressure gradient and effective orifice area (EOA) along with velocity flow field, Reynolds shear stress (RSS), and viscous shear stress (VSS) were calculated. ResultsThe SJM mechanical valve exhibited the greatest EOA (1.96 ± 0.02 cm2), showing superiority of efficiency compared with the same-size Trifecta (1.87 ± 0.07 cm2) and Hancock II (1.05 ± 0.01 cm2) (P < .0001). The TAVs show close EOAs (2.10 ± 0.06 cm2 with Evolut and 2.06 ± 0.03 cm2 with SAPIEN 3; P < .0001). The flow characteristics and behavior downstream of the valves differed depending on the valve type, design, and size. The greater the RSS and VSS the more turbulent the downstream flow. Hancock II displays the greatest range of RSS and VSS magnitudes compared with the same-size Trifecta and SJM. The Evolut displays the greatest range of RSS and VSS compared with the SAPIEN 3. ConclusionsThe results of this study shed light on numerous advancements in the design of aortic valve replacement prosthesis and the subsequent hemodynamic variations. Future surgical and transcatheter valve designs should aim at not only concentrating on hemodynamic parameters but also at optimizing downstream flow properties.

Study of the influence laws of the flow and cavitation characteristics in an injector control valve

AbstractFuel cavitation can cause damage to the structure of an injector control valve, which can further affect the service life of the injector. Therefore, it is of great importance to carry out research on the mechanism of cavitation in injector control valves. In this study, the dynamic evolution of the cavitation and fuel flow characteristics during the opening of a ball valve in a high‐pressure common rail injector control valve were studied. First, a transient CFD simulation of the cavitation during the opening of the control valve was performed using dynamic mesh technology to analyze the evolution and formation mechanism of the cavitation. The cavitation was influenced by the fuel flow velocity, which was affected by the sealing cone angle and the ball valve movement. Additionally, the fuel reflux could effectively inhibit the development of cavitation. By comparing with the pressure, velocity, and mass flow rate of the fuel under conditions without cavitation, it was found that the cavitation had a remarkable effect on reducing the hydraulic shock to the ball valve and sealing cone as well as stabilizing the fluctuation of the fuel velocity in the control chamber. In addition, the cavitation noticeably decreased the fuel mass flow rate (by up to 32% at 0.015 ms) and increased the average pressure in the chamber (by up to 29.1% at 0.01 ms), ultimately leading to a slower response of the control valve. The analysis of different inlet pressures of the control valve indicated that the increase in the inlet pressure caused the cavitation to extend upward along the sealing cone, and that the cavitation ring area and the cavitation strength increased.

Diagnosis of Middle Cerebral Artery Stenosis Using Transcranial Doppler Images Based on Convolutional Neural Network

The purpose of this study was to explore the diagnostic value of convolutional neural networks (CNNs) in middle cerebral artery (MCA) stenosis by analyzing transcranial Doppler (TCD) images. Overall, 278 patients who underwent cerebral vascular TCD and cerebral angiography were enrolled and classified into stenosis and non-stenosis groups based on cerebral angiography findings. Manual measurements were performed on TCD images. The patients were divided into a training set and a test set, and the CNN architecture was used to classify TCD images. The diagnostic accuracies of manual measurements, CNNs, and TCD parameters for MCA stenosis were calculated and compared. Overall, 203 patients without stenosis and 75 patients with stenosis were evaluated. The sensitivity, specificity, and area under the curve (AUC) for manual measurements of MCA stenosis were 0.80, 0.83, and 0.81, respectively. After 24 iterations of the running model in the training set, the sensitivity, specificity, and AUC of the CNNs in the test set were 0.84, 0.86, and 0.80, respectively. The diagnostic value of CNNs differed minimally from that of manual measurements. Two parameters of TCD, peak systolic velocity and mean flow velocity, were higher in patients with stenosis than in those without stenosis; however, their diagnostic values were significantly lower than those of CNNs (P < 0.05). The diagnostic value of CNNs for MCA stenosis based on TCD images paralleled that of manual measurements. CNNs could be used as an auxiliary diagnostic tool to improve the diagnosis of MCA stenosis.

Analisa karakteristik aliran pada fenomena sirkulasi alam fasa-tunggal di Untai FASSIP-01 Mod.2

FASSIP-01 rectangular loop is a facility which owned by PTKRN-BATAN that used for observe the phenomenon of natural circulation in large-scale. This natural circulation phenomenon will be applied as a passive cooling system in nuclear power plant that will be built up in Indonesia. Some FASSIP-01 experiments have done before, but those experiments show that the fluid flow in FASSIP-01 is not in optimal conditions because there are some errors happened and causes some losses. The second modification of FASSIP-01 rectangular loop has purpose to minimize losses happened in previous modification of FASSIP-01. The purpose of this research is to know the characteristics of flow and the trend of the data from the flow in FASSIP-01 mod.2 rectangular loop before do experiments. Simulations is done by using 2-dimensional images and varying the heating temperature at 353,15 K and 363,15 K and the cooler at temperatures of 278.15 K, 283.15 K, 288.15 K and 293.15 K. Based on the simulation results it is known that the velocity flow rate will increase if the temperature in the heating tank is increased, but will decrease if the temperature in the cooling tank is increased. The results of the calculation of the Reynold Number and Nusselt Number based on the velocity flow rate are 2973,668 the lowest and 5775,356 the highest and for the Nusselt number obtained 17,36 and the highest is 28,091.

Simulation of non‐Newtonian flows in a partially filled twin‐screw extruder by smoothed particle hydrodynamics

AbstractThis study considered numerical applications of smoothed particle hydrodynamics (SPH) to non‐Newtonian flow in filled or partially filled conveying elements of twin‐screw extruders (TSEs). The algorithms were validated by using a plane Poiseuille flow. Two geometrical configurations with different gap were investigated. A large sound speed was used to prevent particles penetrating the wall boundary of the complex geometry. The velocity field and flow rate of Newtonian flow and non‐Newtonian flow (power law) in filled model and partially filled model were analyzed. The distribution of particles in partially filled conveying element in one rotation is introduced. The rheological properties of material take important effect on the flow in fully filled and partially filled cases. For the fully filled cases, the screw–barrel clearance takes important effect on the flow due to the leakage flow reducing the flow rate. For the partially filled case, the clearance affects the non‐Newtonian flow by changing the rheological properties of the fluid. The effect of clearance on Newtonian flow is very limited due to no back pressure in the partially filled case. This work prepared a groundwork for the accurate analysis of real extrusion by SPH.

Changes in the microcirculation of the oral mucosa in post-COVID-19 patients not receiving anti-coagulant therapy

Introduction. The outbreak of a new coronavirus infection has become a challenge for the global health system. The COVID-19 infection is directly related to various disorders of the cardiovascular system, including the microcirculatory bed, caused by thrombotic events and deteriorations of blood rheology. Aims. The paper reports on the results of a study of Doppler sonographic parameters changes in patients with a novel coronavirus infection over the past 6 months. Materials and methods. We assessed the oral mucosa microcirculation in three segments using the high-frequency ultrasound dopple-rography. Results. We recorded the linear and volumetric blood flow rates and the Gosling and Purselo indexes in the course of our work. When comparing the obtained average statistical parameters of blood flow velocity, the linear and volumetric blood flow rates in patients of both groups were found to be lain in the same range and the mean values of Vas, Vam, Qas were equal. The mean values of the Purselo resistance index were closer to 1,0 in patients with COVID-19, and the values of the Gosling pulsation index (PI) were on average 53.3 % higher than in the control group. Conclusion. We evaluated the screening capabilities and potential of high-frequency ultrasound dopplerography for use in patients of different age groups and different somatic status.

Alterations in plantar vessel blood flow in patients with mild diabetic peripheral neuropathy

IntroductionEarly identification and treatment of diabetic peripheral neuropathy (DPN) are crucial. Presently, the mechanism of DPN is not very clear, and there are inconclusive conclusions about the influencing factors of...

Effect of Mobile Phone Radiation on Parotid and Submandibular Salivary GlandsAn Ultrasonographic Study

Introduction: In this era of digitalism, mobile phones have become a cultural accessory. Frequent smartphone usage results in possible adverse effects from low radiofrequency radiation and thermal effect emitted by these devices. One of the major concerns is salivary glands as the mobile phones are held against the side of face in close proximity to these glands. Aim: To assess the effect of cell phone radiation on the volume, systolic velocity, salivary flow rate of parotid and submandibular gland between the dominant and non dominant side of mobile phone users. Materials and Methods: A cross-sectional study was conducted in the Department of Oral Medicine and Radiology with the sample size of 100 (50 males and 50 females). Inclusion criteria were based on the frequency of mobile phone usage of more than two hours per day. Mobile phone usage was determined based on patient’s answer to the questionnaire. Ultrasonography (USG) of both parotid and submandibular gland was done bilaterally to measure the volume of the glands and Colour Doppler of external carotid artery to measure systolic velocity. Modified Schirmer tear strips were used bilaterally to measure unstimulated salivary flow rate. The data was entered into MS excel and significance was calculated using independent sample t-test. Results: In parotid gland, mean volume, mean systolic velocity and mean salivary flow rate were of higher value in the dominant side (14.22±2.17 mL; 15.14±3.74 cm/s; 0.37±0.26 mm/5 mins) compared to the non dominant side (13.76±2.14 mL; 14.53±3.39 cm/s; 0.24±0.2 mm/5 mins). In submandibular gland, mean volume, mean systolic velocity and mean salivary flow rate were of higher value in the dominant side (9.60±1.96 mL; 15.70±6.44 cm/s; 0.30±0.22 mm/5 mins) compared to the non dominant side (8.88±2.17 mL; 13.87±4.83 cm/s; 0.26±0.21 mm/5 mins). Conclusion: The volume, systolic velocity of blood flow, the salivary flow rate, of the parotid gland and submandibular gland were significantly more on the dominant side than the non dominant side of mobile phone usage. The study emphasised that prolonged mobile phone usage causes biological changes in salivary glands and its flow rate.

Validation of Non-Invasive Endothelial Shear Stress (ESS) Estimations of Coronary Artery Haemodynamics via In-Silico and In-Vivo Modelling

Endothelial shear stress (ESS) is parallel frictional force exerted by blood flow on the coronary luminal surface and is associated with the development and progression of atherosclerosis. Computational fluid dynamics (CFD) is an engineering method used to analyse fluid flow and has been increasingly applied to simulate ESS. However, current CFD-ESS estimates have never been validated and can display significant variability between research groups. This study aims to provide a comparative analysis of coronary flow using in-silico modelling of coronary flow and particle image velocimetry (PIV). A proximal left anterior descending (pLAD) coronary phantom model was constructed from a patient who had received same day cardiac computed tomography angiography (CTCA) and invasive coronary haemodynamic (Combowire XT) assessment. Patient-specific coronary flow data was applied to CFD boundary conditions and a mock circulatory loop. CFD via PIV under steady flow in a 4-times-scaled model was validated. Same plane velocity field and flow patterns (at mid-luminal of pLAD) from both in-silico and in-vivo data were compared. Mean velocity contours and magnitude were analysed from CFD and PIV. Patient specific average peak velocity obtained from invasive assessment was 0.21m/s. Patient-specific velocity average from CFD was 0.22m/s. The approximated magnitude difference is 4.7%. Velocity contours and flow patterns simulated in the CFD were also comparable with the PIV results. Simulation data from CFD correlate well with experimental PIV results. This early data allows for a non-invasive approach to determine patient-specific coronary haemodynamics (such as velocity profiling and ESS).