Orifice Diameter Research Articles

Investigations into the Approaches of Computational Fluid Dynamics for Flow-Excited Resonator Helmholtz Modeling within Verification on a Laboratory Benchmark

This paper presents the results of a study of self-sustained processes excited in a Helmholtz resonator after a flow over its orifice. A comparative analysis of various approaches to the numerical modeling of this problem was carried out, taking into account both the requirements for achieving the required accuracy and taking into account the resource greediness of calculations, the results of which were verified by comparison with data obtained during a special experiment. The configuration with a spherical resonator with a natural frequency of 260 Hz and an orifice diameter (about 5 cm) in an air flow with a speed of 6 to 14 m/s was considered. A comparison of the calculation results with data obtained in experiments carried out in the wind tunnel demonstrated that the accuracy of calculations of the characteristics of the self-sustained mode using the simplest URANS class model tends to the accuracy of calculations within the large eddy simulation approach formulated in the WMLES model. At the same time, when using WMLES, it is possible to better reproduce the background level of pulsations. From the point of view of resource greediness, expressed in the number of core hours spent obtaining a solution, both models of the turbulence turned out to be almost equivalent when using the same grid models.

Assessing Cavitation Erosion on Solid Surfaces Using a Cavitation Jet Apparatus

This study is dedicated to the examination of cavitation-induced erosion, a critical factor in optimizing the efficiency of hydraulic systems, including hydropower plants and pumping systems. To accomplish this, we conducted a sensitivity analysis utilizing a cavitation jet apparatus (CJA) and an experimental configuration that featured a vertical cylindrical test tank, a submerged nozzle, and an aluminum sample (specifically, alloy 6351 T6). The study maintained a consistent standoff distance of 5 cm and an orifice diameter of 2 × 10-3 m. Two distinct nozzle geometries were tested to assess their influence on cavitation erosion. The outcomes revealed that the 20° conical sharped-edges nozzle resulted in the highest erosion rates, while the commercial nozzle (MEG 2510) caused comparatively less erosion. By standardizing the test duration to 1200 seconds and using a cavitation index of 0.14, the researchers avoided overlapping pits. In summary, the CJA, with these adjustments, demonstrated its effectiveness as a tool for evaluating the resistance of solid surfaces to cavitation.

Analysis and prediction of hydrogen-blended natural gas diffusion from various pipeline leakage sources based on CFD and ANN approach

The influences of pipeline leakage source types on the hazard area distribution caused by accidental hydrogen-blended natural gas leakage are still the focus of gas leakage accidents. Three types of pipeline leakage sources are discussed in this study. Namely, the gas in the vertical pipeline flows from top to bottom, and the leakage orifice is in the pipeline wall; the gas in the vertical pipeline flows from bottom to top, and the leakage orifice is in the pipeline wall; the leakage orifice is in the horizontal pipeline end. The common feature of the above three pipeline leakage sources is that the normal of leakage orifice is parallel to the horizontal plane. The differences in the flow field distribution of hydrogen-blended natural gas released from three pipeline leakage sources are compared through numerical simulation. The effect of various factors on the jet centerline, concentration decay, and maximum horizontal diffusion distance of hydrogen-blended natural gas released from three pipeline leakage sources are analyzed. The predictive models of hydrogen-blended natural gas's maximum horizontal diffusion distance in three pipeline leakage sources under multi-factor coupling are established through a backward propagation neural network (BPNN). Results show that the angle between the gas flow direction in the pipeline and the normal of the leakage orifice, and the background step flow cause differences in the concentration field near the leakage orifice from the three pipeline leakage sources at the same working conditions. In the near-field region, the leakage orifice diameter has the most significant influence on the jet centerline of three hydrogen-blended natural gas jets among three factors. The concentration decay rate of gas released from the horizontal pipeline end is greater than that of gas released from the other two pipeline leakage sources. With the increase of volumetric flow rate, the maximum horizontal diffusion distances of methane released from three pipeline leakage sources all increase, while the maximum horizontal diffusion distances of hydrogen released from three pipeline leakage sources have little change. The predictive models of the maximum horizontal diffusion distance of hydrogen-blended natural gas released from three pipeline leakage sources are established through BPNN. The maximum horizontal hazard distances of the new working conditions are predicted, and the predicted results are in good agreement with the numerical simulation results. This investigation has guiding value for fast and accurate prediction of flammable gas hazard areas.

К вопросам транспортировки гептила железнодорожным транспортом

Purpose: To estimate the properties of heptyl and its effect on the human body and the environment. To provide an overview of the sphere of heptyl application and the features of its transportation by rail. To consider the structural features of the model 15-629 tank car and to perform a calculation to select the optimal crosssectional area for the inlet opening of the relief valve to enhance safety during the transportation of heptyl by the model 15-629 tank car. Methods: To calculate the inner and outer surface areas of the tank shell using the technical characteristics of the six-axis multi-unit tank-car of model 15-629. Next, we will calculate the mass air flow rate through the inlet relief valve and determine the heat transfer occurring due to the external heat dissipation from the tank shell into the surrounding environment. These data are necessary to estimate the equivalent diameter of the inlet relief valve orifice. Results: Thanks to the calculations performed, a more suitable diameter of the inlet safety valve orifice has been determined. This will ensure a safer transportation of highly toxic liquid rocket fuel components used in both Russian launch vehicles (“Kosmos”, “Cyclone”, “Proton”) and international ones (such as American “Titan” rockets, French launch vehicles of the “Ariane”, Chinese rockets of the “Long March” family, and others). Practical significance: Hydrazine-based propellants are more energy-efficient compared to hydrocarbon-based propellants, which has led to an increased usage of Unsymmetrical Dimethylhydrazine (UDMH) in recent years. Due to the rapid growth of space industry, the volume of heptyl transportation by railway has been increasing. In order to prevent technological disasters, calculations have been conducted to determine the diameter of the inlet relief valve to minimize depressurization of the tank car, regardless of temperature conditions.

Steady melting in material extrusion additive manufacturing

PurposeA main cause of defects within material extrusion (MatEx) additive manufacturing is the nonisothermal condition in the hot end, which causes inconsistent extrusion and polymer welding. This paper aims to validate a custom hot end design intended to heat the thermoplastic to form a melt prior to the nozzle and to reduce variability in melt temperature. A full 3D temperature verification methodology for hot ends is also presented.Design/methodology/approachInfrared (IR) thermography of steady-state extrusion for varying volumetric flow rates, hot end temperature setpoints and nozzle orifice diameters provides data for model validation. A finite-element model is used to predict the temperature of the extrudate. Model tuning demonstrates the effects of different model assumptions on the simulated melt temperature.FindingsThe experimental results show that the measured temperature and variance are functions of volumetric flow rate, temperature setpoint and the nozzle orifice diameter. Convection to the surrounding air is a primary heat transfer mechanism. The custom hot end brings the melt to its setpoint temperature prior to entering the nozzle.Originality/valueThis work provides a full set of steady-state IR thermography data for various parameter settings. It also provides insight into the performance of a custom hot end designed to improve the robustness of melting in MatEx. Finally, it proposes a strategy for modeling such systems that incorporates the metal components and the air around the system.

Static and Dynamic Performances of Novel Aerostatic Bearings with Primary and Secondary Orifice Restrictors

Aerostatic bearings are crucial support components in ultra−precision manufacturing equipment. However, improvements in the load−carrying capability (LCC) of aerostatic bearings often lead to higher intensity nano−vibrations. This paper introduces a novel primary and secondary orifice restrictor (PSOR) designed to simultaneously enhance the LCC and mitigate nano−vibrations in aerostatic bearings. The static performance of complex turbulent flows occurring within the chamber of aerostatic bearings with PSORs was investigated. The dynamic performance of the turbulent flows was analyzed through 3D transient numerical simulation using the large eddy simulation method. The LCC and nano−vibration acceleration were measured experimentally, and the results indicated that the design of the secondary orifice diameter could enhance LCC and mitigate nano−vibrations, consistent with theoretical predictions. The accuracy of the proposed model was validated, confirming the effectiveness of PSOR. In the experiments, an aerostatic bearing with a secondary orifice diameter of 0.1 mm exhibited the lowest LCC and largest nano−vibration. Conversely, an aerostatic bearing with a secondary orifice diameter of 0.26 mm exhibited the highest LCC and weakest nano−vibration. This study provides insights into the formation mechanism of turbulent vortex and interaction mechanism among the primary orifice and secondary orifices in aerostatic bearings with a PSOR.

Experimental investigation of the influence of pre-chamber structural parameters on combustion and emission characteristics of a high compression ratio SI engine

The passive pre-chamber exhibits great potential for practical applications in the internal combustion engine due to its simple structure. However, it faces difficulties in scavenging process, making optimization of pre-chamber structure particularly important. In this study, the effects of pre-chamber ignition systems with different structures and original spark ignition were conducted on a high compression ratio direct-injection SI engine to investigate the combustion, performance, and emission characteristics. The results show that the increase in pre-chamber volume weakens the in-cylinder combustion process and engine performance, while increasing the pre-chamber orifice diameter can enhance the combustion stability at medium to high loads, but will weaken the engine performance at low load. Compared to spark ignition, pre-chamber ignition results in an earlier 50% combustion position, a shorter combustion duration and lower COVIMEP, with these effects becoming stronger as load increases. At high load, the pre-chamber ignition (PC1) advances the 50% combustion position by 5.6°CA and shortens the combustion duration by 16.7%. In addition, the indicated thermal efficiency of the pre-chamber ignition achieves an increase of 0.84% at the optimal point and 2.5% at high load. Overall, using the smaller orifice diameter and volume in the pre-chamber can improve in-cylinder combustion process and increase thermal efficiency across the load range. For emission analysis, the pre-chamber ignition leads to an increase in NOx and HC emissions due to the influence of in-cylinder combustion temperature and quenching effect, while the CO emissions are similar to spark ignition.

Incidence, impact and predictors of residual device patency after left atrial appendage closure with the LACbes device

BackgroundThe residual device patency (RDP) after left atrial appendage closure (LAAC) with the LACbes device has not been specifically explored in atrial fibrillation (AF) patients. This study aims to explore the incidence, impact and predictors of RDP detected by cardiac computed tomography angiography (CCTA) post LAAC. MethodsAF patients implanted with the LACbes device were prospectively enrolled. CCTA device surveillance was performed at 3 months post-procedure. Major adverse events (MAEs), including stroke/transient ischemic attack, major bleeding and all-cause death, were evaluated. ResultsAmong 141 patients with CCTA surveillance, 56 (39.7%) showed no visible leak and 85 (60.3%) showed RDP. During the median follow-up of 443 [232, 706] days, the presence of RDP was not associated with an increased risk of MAEs (adjusted hazard ratio [HR]: 4.07, 95% confidence interval [CI]: 0.49–34.24, p = 0.196), while peri-device leak (PDL) at the lobe was associated with heightened risks of MAEs (adjusted HR: 6.85, 95% CI: 1.62–28.89, p = 0.009). In patients with PDL at the lobe, antiplatelet after 6 months (HR: 0.20, 95% CI: 0.05–0.91, p = 0.038) was independent protective predictor of MAEs. Besides, current smoking (odds ratio [OR]: 7.52, 95% CI: 2.68–21.08, p < 0.001) and maximum diameter of LAA orifice (OR: 1.16, 95% CI: 1.00–1.34, p = 0.048) were independent predictors of PDL at the lobe. ConclusionsPresence of PDL at the device lobe detected by CCTA at 3-month post LAAC with LACbes is associated with unfavorable prognosis in AF patients.Clinical trial registration: ClinicalTrials.gov Identifier: NCT03788941.

Five-year follow-up after percutaneous pulmonary valve implantation using the Venus P-valve system for patients with pulmonary regurgitation and an enlarged native right ventricular outflow tract.

Percutaneous pulmonary valve implantation (PPVI) with the self-expandable Venus P-valve system is a promising treatment for patients with pulmonary regurgitation (PR) and a native right ventricular outflow tract (RVOT). However, limited data is available regarding its midterm outcomes. This study assessed the midterm clinical and echocardiographic outcomes following Venus P-valve implantation. From 2013 to 2018, 55 patients with moderate or severe PR after surgical RVOT repair with a transannular or RVOT patch were consecutively enrolled from six hospitals in China. Five-year clinical and echocardiographic outcomes were collected and evaluated. The primary endpoint was a freedom from all-cause mortality and reintervention. At 5 years, the primary endpoint was met for 96% of patients, corresponding to a freedom from all-cause mortality of 96% (95% confidence interval [CI]: 86%-99%) and freedom from reintervention of 98% (95% CI: 87%-100%). Endocarditis was reported in five patients (four patients within 1 year and one patient at 5 years) following PPVI. Transpulmonary gradient and stent orifice diameter remained stable compared to at discharge (p＞0.05). No paravalvular leak was reported while only 1 patient gradually increased to moderate PR during follow-up. Significant improvement of RV diameter and LVEF(p＜0.001) sustained over the 5-year follow-up, in consistent with remarked improved New York Heart Association(NYHA) functional class (p＜0.001). The 5-year results of the China VenusP Study demonstrated the midterm benefits of Venus P-valve implantation in the management of patients with severe PR with an enlarged native RVOT by providing sustained symptomatic and hemodynamic improvement.

Experiment and numerical investigation on flow characteristics and near-field structure of dense phase CO2 pipeline leakage

Accidental leakage of high-pressure CO2 is not only a safety hazard, but also may have a great negative impact on the operating efficiency of some circulating systems. To analyze the accident hazards and improve the ability to predict the transient release flow behavior of high-pressure CO2, a set of small pipeline leakage test equipment was built. The changes of near-field pressure, temperature, and jet structure under different upstream pressure (6–12 MPa), temperature (280–300 K) and orifice diameter (5 mm, 10 mm, 20 mm, 40 mm) were analyzed. Secondly, as a supplement to the experiment, the near-field CO2 gas phase distribution and critical mass flow were studied by numerical model. The results show that the near field pressure peak is negatively correlated with the initial upstream pressure, but positively correlated with the release diameter. In addition, the increase of upstream initial pressure and release diameter will lead to the increase of radial development range of near-field jet cloud. Based on the numerical results, an empirical correlation of critical mass flow based on upstream initial conditions and RHP is established. The error between the experimental data and the predicted value within the range of the correlation is within ± 18%. The research data and results can help to enhance the understanding of the rapid release characteristics of high-pressure CO2 in the near field region and provide a basis for the study of CO2 diffusion in the far field region and the leakage risk assessment.

Effect of leakage source condition on the unignited hydrogen released issuing through a horizontal realistic pipeline geometry

An unignited gas release experiment system for the schlieren visualization and concentration quantitative measurement is designed and built to investigate the diffusion and concentration distribution features of turbulent hydrogen jets issuing from a realistic pipeline geometry. Helium is used in place of hydrogen for safety reasons. The spatial and temporal evolution of the asymmetry of turbulent helium jets was studied. The influence mechanisms of the volumetric flow rate (Q), the ratio of orifice diameter to the inner diameter of pipeline (R), and the angle between the normal of the leakage orifice and the opposite direction of gravity (θ) on the asymmetric concentration distribution are revealed. The experimental results show that the diffusion angle (α) and the inclination angle (β) of the turbulent helium jet are the largest when Q is 15 SLPM, R is 0.3, and θ is 0°, and the asymmetric feature of the turbulent helium jet is obvious. As the Q increased, the slope k of the inverse helium concentration (1/volume fraction) and a scaled distance L (L = (x/d)·(ρa/ρ0)1/2) became small. The increase of Q aggravated the concentration attenuation caused by the volumetric flow rate and the asymmetry jet. As R increased, the slope k of the inverse helium concentration and a scaled distance L first decreased and then increased. The slope k got the minimum value when R was 0.3. The downward movement of the leakage orifice position increased the turbulent intensity near the leakage orifice. This work can provide theoretical support for accident prevention and emergency treatment of hydrogen leakage accidents in long-distance pipeline low-pressure hydrogen transportation.

Generation of microbubbles via a tapered capillary

We propose a novel method for efficient production of microbubbles based on a tapered capillary with an interiorly attached filament. When gas–liquid displacement driven by an input pressure occurs in the capillary, the gas cone ruptures close to the orifice of the capillary. The generated microbubbles can be pushed out of the capillary and collected by a liquid tank when the pressure is appropriately selected. A liquid column is employed in the straight part of the capillary, which can sustain the liquid film near the capillary orifice and hence the bubble generation by transporting liquid along the filament. Within the working pressure range, increasing the input air pressure leads to a decrease in the microbubble diameter. The minimum diameter of the microbubbles is approximately equal to the orifice diameter of the tapered capillary. In our experiments, microbubbles with a minimum diameter of 1.56 μm can be realized. Theoretically, we derive a one-dimensional unsteady lubrication equation describing the evolution of the gas–liquid interface in a tapered tube. The bubble pinch-off is justified by the numerical solution of the lubrication equation. In particular, the predicted bubble diameters are in agreement with the experimental measurements.

Controlled generation of high-frequency liquid metal microdroplets

Liquid metal (LM) microdroplets with high conductivity and fluidity have drawn extensive attention in the field of electronics, biomedicine, and catalysis. The properties of LM droplets, e.g., melting points, electrical actuation, and stability, are affected by their sizes. Continuous generation of LM microdroplets with precisely controlled size will benefit their applications, which however, remains an outstanding challenge. In this study, we have designed a scalable high frequency droplet generator for the liquid metal (EGaIn) that works on the principle of manipulating the electrohydrodynamic behaviour of EGaIn. By applying electric potentials < − 0.75 V vs Ag/ AgCl, EGaIn droplets with uniform sizes can be rapidly and continuously generated. The electric potential effectively tunes the thickness of the oxide layer on the EGaIn surface which in turn modulates the surface tension of the EGaIn and induces the generation of consistent sized EGaIn droplets. The size of the EGaIn microdroplets can be varied between 40 and 200 µm, depending on the electric potential applied and the diameter of the exit orifice. Droplet generation using this method requires relatively low energies, i.e., 2.77 × 10-7 kWh, and is coupled with high frequency droplet generation ∼ 60 droplet/min. The scalability of this droplet generation methodology can be further increased via design of an array of exit orifice. With the presence of surfactants, these EGaIn droplets can remain well-dispersed without coalescing. This considerably widens their capability for further applications.

Study on the electron emission characteristics of a thermal emission cathode with grid for micro-electric thruster

The Thermal Emission Cathode with Grid (TECG) is a type of cathode that operates without a working medium based on electric field modulation, which can be effectively adapted with micro-electric thrusters to perform high-precision space science missions. This research first analyzes the thermal electron emission theory, and the key dimensional and electrical parameters of the TECG, such as the grid width, the grid-emitter distance, the grid orifice diameter, the grid voltage, and the anode voltage, are simulated using the electromagnetic simulation software OPERA to obtain the optimal combination. Subsequently, the TECG was designed and machined using the parameters above for experimental testing and verification against the simulation results. The relative error between the experimental and simulation results was less than 20%. Under specific working conditions, the TECG’s total emission capability can be increased by approximately 8 times, and the maximum emission current can reach up to 27.525 mA. Afterward, the research also discusses the electric field distribution in the entire space of the TECG, along with the electron distribution behavior caused by the electric field. Finally, after pointing out its shortcomings, the research provides guidance and prospects for future related work.

Research and prediction of pipeline inspection gauges velocity based on simulation and neural network

Pipeline transportation is a highly efficient transportation mode, and pipeline inspection gauge (PIG) is a widely used pipeline cleaning, detection and maintenance device. The PIG's ability to fulfill its intended purpose hinges heavily on its motion velocity. And it is vital to predict and control the velocity of PIG to ensure optimal functioning. This paper establishes several models with different rotary valve orifice numbers, orifice diameters, valve openings, and sealing disc compression amounts. The effects of the factors on PIG force state and velocity are analyzed by finite element method (FEM). With these simulation outcomes, the paper establishes velocity prediction models based on polynomial fitting, support vector machine (SVM) and neural network methods. In addition, by combining neural networks with genetic algorithms, the PIG size is optimized. The results demonstrate that compared with polynomial fitting and SVM, neural networks are more convenient and accurate and have a broader application prospect.

Evaluation of Molten Steel Flow Behaviors in a Multistrand Tundish via Numerical Simulation and Grey Relational Analysis with a New Dimensionless Operator

Optimizing the tundish structure can effectively improve billet or solid product quality. The correlation between the structural parameters of the baffle and the flow characteristics of molten steel in a tundish is a prerequisite for tundish structural optimization. In this study, molten steel flow behaviors are stimulated in a five‐strand tundish using computational fluid dynamics. The behaviors are characterized by the dead‐zone ratio of the entire tundish and the flow consistency of five strands at the outlets. Further, the influences of different structural parameters on the characteristics are analyzed, and the degree of influence is evaluated using grey relational analysis (GRA). Four traditional nondimensionalization operators are used for GRA. However, the results obtained from different operators are inconsistent. Therefore, a benchmark deviation dimensionless operator is proposed to improve the accuracy of GRA. The improved grey correlation degrees are consistent with the results obtained through numerical simulation. The rank of the grey correlation degree indicates that the diameter and inclination angle of Orifice B, which is at the lower position of the baffle, are highly correlated with the dead‐zone ratio. The inclination angles should have a larger correlation degree for flow consistency than the orifice diameter.

Noise and Jet Momentum of Synthetic Jet Actuators with Different Orifice Configurations

Sound pressure levels and flow characteristics of a synthetic jet actuator (SJA) are investigated experimentally using the following orifice configurations: a) a slender rectangular slot orifice and b) an array of circular orifices with two different orifice diameters. All configurations have similar total orifice neck area, orifice height, and cavity volume, resulting in a similar Helmholtz frequency. Experiments are conducted for orifices mounted on a flat plate under a quiescent condition. The mean jet velocity exhibits resonant peaks at several excitation frequencies, which also gave rise to the sound pressure levels. The resonant frequencies and peak jet velocities were found to depend on the excitation amplitude and orifice configuration. Investigation of the jet momentum penetration into the quiescent air above the different orifice configurations shows that the momentum issuing from the rectangular slot decays much quicker than that of the circular orifices, irrespective of whether the SJA is excited at resonance or not. The most favorable performance (i.e., the highest momentum in the jet core) was obtained with the array of circular orifices having a smaller orifice diameter, even at off-resonance excitations. The work herein shows the possibility of reducing the SJA noise by 8–10 dB by operating the SJA at a frequency away from the Helmholtz frequency while still achieving comparable levels of jet momentum penetration into the crossflow.

Investigation on dynamic stress of the discharge valve in the transcritical CO2 compressor

During the development of the 3000 r·min−1 transcritical CO2 compressor, the discharge valve plate is fractured frequently. To study the dynamic stress of discharge valve in CO2 compressor, a simplified FSI model is established. Both the stress variation of the discharge valve plate during the operation of the compressor and the influence of different parameters on dynamic stress of the valve plate have been studied. The results show that the pressure difference between suction and discharge is the primary factor affecting dynamic stress of the valve plate. The failure of the valve plate is partly because of the alternating stress caused by the valve plate hitting the limiter, but principally because of the sag stress to discharge orifice caused by the pressure difference on the valve plate. When the discharge pressure rises from 8 MPa to 12 MPa, the impact stress and sag stress of the valve plate increase by 76.7 % and 87.5 % respectively. When the diameter of discharge orifice decreases from 12 mm to 6 mm, the maximum stress decreases from 287.7 MPa to 136.8 MPa, with a reduction of 52.4 %. The results show that reducing diameter of discharge orifice is an effective way to reduce the dynamic stress.

Hypoglossal canal: an osteological and morphometric study on a collection of dried skulls in an Italian population: clinical implications

BackgroundThe hypoglossal canal is a dual bone canal at the cranial base near the occipital condyles. The filaments of the hypoglossal nerve pass through the canal. It also transmits the meningeal branch of the ascending pharyngeal artery, the venous plexus and meningeal branches of the hypoglossal nerve. The hypoglossal nerve innervates all the intrinsic and extrinsic muscles of the tongue except the palatoglossal and is fundamental in physiological functions as phonation and deglutition. A surgical approach to the canal requires knowledge of the main morphometric data by neurosurgeons.MethodsThe present study was carried out on 50 adult dried skulls: 31 males: age range 18–85 years; 19 females: age range 26–79 years. The skulls came from the ''Leonetto Comparini'' Anatomical Museum. The skulls belonged to people from Siena (Italy) and its surroundings (1882–1932) and, therefore, of European ethnicity. The present study reports (a) the osteological variations in hypoglossal canal (b) the morphometry of hypoglossal canal and its relationship with occipital condyles. One skull had both the right and left hypoglossal canals occluded and, therefore, could not be evaluated. None of the skulls had undergone surgery.ResultsWe found a double canal in 16% of cases, unilaterally and bilaterally in 2% of cases. The mean length of the right and left hypoglossal canals was 8.46 mm. The mean diameter of the intracranial orifice and extracranial orifice of the right and left hypoglossal canals was 6.12 ± 1426 mm, and 6.39 ± 1495 mm. The mean distance from the intracranial end of the hypoglossal canal to the anterior and posterior ends of occipital condyles was 10,76 mm and 10,81 mm. The mean distance from the intracranial end of the hypoglossal canal to the inferior end of the occipital condyles was 7,65 mm.ConclusionsThe study on the hypoglossal canal adds new osteological and morphometric data to the previous literature, mostly based on studies conducted on different ethnic groups.The data presented is compatible with neuroradiological studies and it can be useful for radiologists and neurosurgeons in planning procedures such as transcondilar surgery. The last purpose of the study is to build an Italian anatomical data base of the dimensions of the hypoglossal canal in dried skulls..

Application of computed tomographic angiography and echocardiography in predicting left atrial appendage thrombosis in patients with non-valvular atrial fibrillation.

We aimed to explore the application of computed tomographic angiography (CTA) and echocardiography in predicting left atrial appendage (LAA) thrombosis in patients with non-valvular atrial fibrillation. The clinical data of 164 atrial fibrillation patients receiving cardiac CTA and real-time three-dimensional transoesophageal echocardiography (RT-3D-TEE) were retrospectively analysed. The patients were divided into group A (anticoagulant treatment group, n = 112) and group B (selective anticoagulant treatment group, n = 52) according to the CHA2DS2-VASc score, which scored for the presence or absence of congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke/transient ischaemic attack, vascular disease, age 65-74 years and gender (female). The CHA2DS2-VASc score was used to predict risk of thromboembolism from atrial fibrillation. The correlations of CHA2DS2-VASc score with CTA-based LAA classification and RT-3D-TEE measurement parameters were explored using Spearman's analysis. Receiver operating characteristic (ROC) curves were plotted to explore the predictive value of CTA and RT-3D-TEE for LAA thrombus. There were significant differences in age, disease course, hypertension, diabetes mellitus, coronary heart disease, heart failure, stroke/transient ischaemic attack/thromboembolism, vascular disease, B-type natriuretic peptide and serum uric acid levels, CHA2DS2-VASc score, LAA classification, left ventricular ejection fraction (LVEF), left atrial diameter (LAD), maximum diameter of LAA orifice, minimum diameter of LAA orifice and LAA length (p < 0.05). CHA2DS2- VASc score was positively correlated with cauliflower LAA, LAD, maximum diameter of LAA orifice, minimum diameter of LAA orifice and LAA length, and negatively correlated with LVEF (p < 0.001). ROC curve analysis indicated that CTA, RT-3D-TEE and CHA2DS2-VASc score had similar predictive values for risk of LAA thrombosis in atrial fibrillation patients, with the areas under the curve being 0.778, 0.814 and 0.792, respectively. Both CTA and RT-3D-TEE had high predictive values for LAA thrombosis in atrial fibrillation patients.