Ratio Of Long Axis Research Articles

Numerical Analysis Of Natural Convection In A Closed Circular Cavity With A Elliptical Heater

The natural convection heat transfer in a closed circular cavity containing a constant temperature elliptic heating body was studied by finite volume method. The influences of Rayleigh number Ra, relative size of heating element and rotation Angle on flow and heat transfer in the cavity are discussed. The variation range of Rayleigh number is 103 ~ 106, the variation range of length-diameter ratio of elliptic long axis to cavity diameter is 0.1 ~ 0.4, and the variation range of rotation angle is 0° ~ 90°.The results show that the changes of the above three parameters can affect the structure of temperature field and flow field in the cavity. Increasing the Rayleigh number, decreasing the size of the heating element and increasing the rotation Angle of the heating element will be more conducive to the heat transfer in the cavity. The research results can provide theoretical basis for the heat dissipation and management of electronic equipment.

Experimental investigation into segregation behavior of spherical/non-spherical granular mixtures in a thin rotating drum

This paper uses physical experiments to investigate the segregation behavior of binary granular mixtures in a quasi-two-dimensional rotating drum. Spherical polyformaldehyde (POM) beads and cylindrical red beans constitute the granular mixtures. The effects of particle size, particle density, and particle shape interplay during the segregation process in the spherical/non-spherical particulate system. A long-axis ratio (LAR), the ratio of the spherical POM beads' diameter to the red beans' primary dimension, was defined to explore the particle shape effect. The experimental results show that the long-axis ratio and the rotation speed play substantial roles in the granular segregation behavior. As the long-axis ratio increases, the steady-state segregation intensity decreases. An increase in the rotation speed enhances the segregation of the binary granular mixtures for each long-axis ratio studied here. In addition, the average velocity and granular temperature of spherical POM beads increase as the long-axis ratio increases. Both properties also increase as the rotation speed increases. The dynamic angle of repose for the binary mixtures increases with the increase in the long-axis ratio. Most interestingly, reverse granular segregation does occur at a long-axis ratio of 0.70 with the cylindrical red beans in the core and the spherical POM beads at the periphery for each rotation speed studied here. This reverse segregation has not been observed in previous studies. This highlights the substantial impact of particle shape on the granular segregation in binary granular mixtures.

Echocardiographic characteristics and clinical outcomes in fetuses with pulmonary stenosis or pulmonary atresia with intact ventricular septum

To summarize echocardiographic characteristics of the anatomy and hemodynamic and clinical outcomes in fetuses with isolated pulmonary stenosis (PS) or pulmonary atresia with intact ventricular septum (PA/IVS). This was a single-center retrospective study of fetuses with isolated PS or PA/IVS. Echocardiographic variables and clinical outcomes after delivery were evaluated and compared. Between 2016 and 2021, 115 livebirths with isolated PS or PA/IVS were included. Proportion of fetuses with mild, moderate and critical PS and PA/IVS was 41.7%, 18.3%, 26.1% and 13.9%. Fetuses with more severe PS had worse anatomic and hemodynamic profiles. Specifically, the cardiothoracic ratio, pulmonary valve (PV) velocity, degree and velocity of tricuspid regurgitation increased as PS severity increased; and the pulmonary artery/aorta ratio, right ventricle/left ventricle long-axis (TV/MV) ratio, tricuspid valve/mitral valve annulus (TV/MV) ratio, and tricuspid valve inflow duration/cardiac cycle ratio decreased as PS severity increased (P <0.001 for all). PV velocity ≥2m/s predicted PV pressure ≥40mm Hg after delivery, with an AUC of 0.81; TV/MV ratio combined with RV/LV ratio predicted clinical outcomes, with an AUC of 0.88. Live births with more severe PS had higher mortality rate (mild 0 vs. moderate 0 vs. critical 11% vs. PA-IVS 36%) and lower rate of developing bi-ventricles (mild 100% vs. moderate 95% vs. critical 89% vs. PA-IVS 36%). Findings of this study help better understand the anatomy and hemodynamic and clinical outcomes in fetuses with isolated PS or PA/IVS, which could have implications for prenatal counseling and prediction of fetal outcome.

Fetal pulmonary valvuloplasty for pulmonary atresia with intact ventricular septum: a single-center clinical experience.

Fetal pulmonary valvuloplasty for pulmonary atresia with intact ventricular septum: a single-center clinical experience.

Distinguishing mesorectal tumor deposits from metastatic lymph nodes by using diffusion-weighted and dynamic contrast-enhanced magnetic resonance imaging in rectal cancer.

This study aimed to identify whether apparent diffusion coefficient (ADC) values and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) parameters are helpful in distinguishing mesorectal tumor deposits (TD) from metastatic lymph nodes (MLN) in rectal cancer (RC). Thirty patients (59 lesions, including 30 TD and 29 MLN) with RC who underwent pretreatment-MRI between February 2016 and August 2018 were enrolled. The morphological features, ADC values, and semi-quantitative parameters of DCE-MRI, including relative enhancement (RE), maximum enhancement (ME), maximum relative enhancement (MRE), time to peak (TTP), wash-in rates (WIR), wash-out rates (WOR), brevity of enhancement (BRE), and area under the curve (AUC) were measured on lesions (TD or MLN) and RC. The parameters were compared between TD and MLN, tumor with and without TD group by using Fisher's exact test, independent-samples t-test, and Mann-Whitney U test. The ratio (lesion-to-tumor) of the parameters was compared between TD and MLN. Receiver operating characteristic curve analysis and binary logistic regression analysis were used to assess the diagnostic ability of single and combined metrics for distinguishing TD from MLN. The morphological features, including size, shape, and border, were significantly different between TD and MLN. TD exhibited significantly lower RE, MRE, RE-ratio, MRE-ratio, ADCmin-ratio, and ADCmean-ratio than MLN. RE-ratio showed the highest AUC (0.749) and accuracy (77.97%) among single parameters. The combination of DCE-MRI and DWI parameters together showed higher diagnostic efficiency (AUC = 0.825). Morphological features, ADC values, and DCE-MRI parameters can preoperatively help distinguish TD from MLN in RC. • DWI and DCE-MRI can facilitate early detection and distinguishing mesorectal TD (tumor deposits) from MLN (metastatic lymph nodes) in rectal cancer preoperatively. • TD has some specific morphological features, including relatively larger size, lower short- to long-axis ratio, irregular shape, and ill-defined border on T2-weighted MR images in rectal cancer. • The combination of ADC values and semi-quantitative parameters of DCE-MRI (RE, MRE) can help to improve the diagnostic efficiency of TD in rectal cancer.

Optimization of four-Chamber and eccentric ellipse mufflers hybridized with multi-Segment perforated/non-perforated tubes

Muffler with circular section and inner symmetric acoustical elements has been habitually used in industry. In order to improve the acoustical performance, an advanced eccentric muffler having ellipse cross-section, multiple chambers, and multi-segment perforated/non-perforated tubes is presented. Concerning about high order wave effect to the muffler, a finite element method (FEM) run on COMSOL package is adopted. In addition, the influence of sound transmission loss with respect to various geometric parameters has been explored. In order to simplify the optimization process, a simplified objective function established by an Artificial Neural Network (ANN) and FEM has been implemented and connected to a Genetic Algorithm (GA). Two case studies of muffler optimization for two kinds of design parameter sets (one of Lin and Lout and the other of Lin1 and Lout 1) are introduced. Two targeted frequencies (1000 Hz and 2500 Hz) are selected and applied in the two cases’ muffler optimization. Simulated results reveal that the acoustical influence relating to various geometric parameters is huge. The sound attenuation will increase in the low frequency region if the curvature ratio δ (ratio of long axis to short axis in ellipse) or the X (horizontal length of the muffler’s body) increases. Consequently, the study demonstrates a methodology in the optimization of a four-chamber ellipse and eccentric muffler internally inserted with multi-segment perforated/non-perforated tubes.

Application of 3D printed nasal vestibular support in the treatment of anterior nostril stenosis

Objective:To evaluate the efficacy of 3D printed nasal vestibular support on the recovery of nasal ventilation function and nostril shape after nostril stenosis treatment. Methods:Thirty-eight patients with unilateral traumatic nasal vestibular stenosis were selected and treated with 3D printed nasal vestibular support after operation. Subjective evaluation indicators, objective nostril local morphological and structural parameters, and nasal airflow dynamics parameters by numerical simulation were used. To evaluate the nostril morphological and nasal functional recovery after treatment. Results:The subjective nasal congestion and nostril symmetry satisfaction VAS scores of the patients after nasal vestibular support treatment were improved to varying degrees compared with those before surgery; The nostril morphological parameters showed that the Δlong-axis ratio and Δ short-axis ratio were significantly decreased after nasal vestibular support therapy （0.09±0.09 and 0.16±0.13） compared with those before surgery（0.21±0.20 and 0.28±0.21） respectively（P<0.01）. And the cross-sectional area of the nasal valve on the stenotic side nasal cavity increased from（0.40±0.27） cm² before operation to （0.71±0.26） cm² after treatment（P<0.01）; The nasal resistance on the stenosis side nasal cavity also decreased from （0.036±0.024） Pa·s/mL before operation to （0.022±0.008） Pa. s/mL after treatment（P<0.01）, and the total nasal resistance was decreased from （0.033±0.02） Pas/mL before operation to （0.021±0.007）Pa. s/mL after treatment（P<0.01） ; It also showed that NWE（nasal warming efficiency） and NHE（nasal humidification efficiency） on the stenotic side nasal cavity were significantly decreased after nasal vestibular support therapy（[95.92±2.8]% and [94.55±4.17]%） compared with those before surgery （[97.94±1.97 ]% and [96.19±2.94]%） respectively（P<0.01）. Conclusion:The 3D printed nasal vestibular support for postoperative support treatment on patients with anterior nostril stenosis can reflect the advantages of personalized treatment and allow patients to obtain satisfactory results, and the use of individually designed 3D printed nasal vestibular support can make the shape of anterior nostrils and nasal cavity normal ventilation function recover well, its clinical application prospect is worth looking forward to.

Performance enhancement and optimization for rod‐baffle heat exchangers with twisted oval tubes

AbstractTwisted oval tubes were proposed to be installed in rod‐baffle heat exchangers (RBHXs) to enhance heat transfer performance. A comparison between RBHXs with twisted oval tubes and those with circular tubes is performed. The results show that the heat transfer coefficient (h) per unit pressure drop (Δp) of RBHXs with twisted oval tubes is larger than 36.01%~100.24% compared with that of circular tubes when Reynolds numbers are 4577~22 889, and heat transfer enhancement is more obvious under lower inlet velocity. Then the structural parameters of RBHXs with twisted oval tubes are optimized using the response surface model and genetic algorithms. The results show that the h decreases first and then remains constant with the increase of the twisted pitch length, and decreases first and then rises again with the increase of the ratio of long axis to short axis. The Δp almost keeps constant with increasing twisted pitch length and decreases by 36.67% with the increase in the ratio of long axis to short axis. The comprehensive performance index h/Δp of the RBHXs with twisted oval tubes is enhanced by an average of 26.42% compared with that of original structure. The research results have a good guideline for heat transfer enhancement and the structural design of RBHXs.

Fetal Pulmonary Valvuloplasty in Fetuses with Right Ventricular Outflow Tract Obstructive Disease: Experience and Outcome of the First Five Cases in China.

The current study was to report our initial experiences of fetal pulmonary valvuloplasty (FPV) for fetuses with pulmonary atresia with intact ventricular septum (PA/IVS) and critical pulmonary stenosis (CPS), including case selection, technical feasibility, and the effects of FPV on utero and postnatal outcome. Two fetuses with PA/IVS and three fetuses with CPS were enrolled between September 2016 and April 2018. All fetuses were with concomitant severe right ventricular dysplasia and growth arrest. Parameters of right cardiac development and hemodynamics, including tricuspid/mitral annulus ratio (TV/MV), right ventricle/left ventricle long-axis ratio (RV/LV), tricuspid valve inflow duration/cardiac cycle ratio (TVI/CC), degree of tricuspid regurgitation (TR), and blood flow direction of arterial duct and ductus venosus, were evaluated using echocardiogram. FPV was performed trans-abdominally under ultrasound guidance. Echocardiogram was performed post-FPV and every 2-4weeks thereafter until delivery. The median gestational age at the time of FPV was 28weeks. From technical perspective, pulmonary balloon valvuloplasty was successfully performed and the opening of pulmonary valve was improved in all fetuses in 2-4weeks. However, progressive restenosis was observed in four fetuses with gestation advancing, and re-atresia occurred in two PA/IVS fetuses at 36th and 37th weeks' gestation, respectively. The growth trajectories of TV/MV, RV/LV, and TVI/CC were improved in the 1st week after FPV and then slowed down along with pulmonary valve restenosis. All fetuses were born alive and underwent postnatal interventions, including pulmonary balloon valvuloplasty in three fetuses and surgical procedures in two fetuses. During follow-up, three fetuses turned to be biventricular, one became one and a half ventricular at 1-year old, and one died of neonatal infection. Although pulmonary valve restenosis might occur as gestation advancing, FPV seems to be a safe and feasible procedure to improve the growth trajectories of right heart for fetuses with PA/IVS and CPS.

Stability study and optimization design of small-spacing two-well (SSTW) salt caverns for natural gas storages

Abstract A small-spacing two-well salt (SSTW) cavern is a relatively new type of cavern. As this type of cavern is less frequently used in underground natural gas storages, study on its stability is quite limited. To promote the application of this type of cavern and accelerate the construction of underground salt cavern gas storages, stability analysis and optimization design of this type of cavern are indispensable to the security of underground natural gas storages. In this paper, numerical calculation and parameters analysis were performed to analyze the effects of internal gas pressure and ratio of long axis to short axis (RLS) on the stability of SSTW caverns. The results show that internal gas pressure has an influence on the stability of SSTW caverns and low pressure should be limited in terms of duration and magnitude. And the ratio of long axis to short axis (RLS) has limited influence on the stability of a SSTW cavern by ways of volume loss rate and roof settlement. Overall, the SSTW cavern behaves similar stability state with that of a SW cavern. In addition, a flatter roof shape appears under greater Ratio value (RLS) and thus a thicker roof salt rock thickness is suggested for engineering design. The most different between them are the waist displacement along short axis, therefore the pillar width close to the adjacent cavern should be a certain lengthened at this direction.

Non-invasive MR assessment of the microstructure and microcirculation in regional lymph nodes for rectal cancer: a study of intravoxel incoherent motion imaging

BackgroundThe aim of this study is to evaluate the microstructure and microcirculation of regional lymph nodes (LNs) in rectal cancer by using non-invasive intravoxel incoherent motion MRI (IVIM-MRI), and to distinguish metastatic from non-metastatic LNs by quantitative parameters.MethodsAll recruited patients underwent IVIM-MRI (b = 0, 5, 10, 20, 30, 40, 60, 80, 100, 150, 200, 400, 600, 1000, 1500 and 2000 s/mm2) on a 3.0 T MRI system. One hundred sixty-eight regional LNs with a short-axis diameter equal to or greater than 5 mm from 116 patients were evaluated by two radiologists independently, including 78 malignant LNs and 90 benign LNs. The following parameters were assessed: the short-axis diameter (S), long-axis diameter (L), short- to long-axis diameter ratio (S/L), pure diffusion coefficient (D), pseudo-diffusion coefficient (D*), and perfusion factor (f). Intraclass correlation coefficients (ICCs) were calculated to assess the interobserver agreement between two readers. Receiver operating characteristic curves were applied for analyzing statistically significant parameters.ResultsInterobserver agreement of IVIM-MRI parameters between two readers was excellent (ICCs> 0.75). The metastatic group exhibited higher S, L and D (P < 0.001), but lower f (P < 0.001) than the non-metastatic group. The area under the curve (95% CI, sensitivity, specificity) of the multi-parameter combined equation for D, f and S was 0.811 (0.744~0.868, 62.82%, 87.78%). The diagnostic performance of the multi-parameter model was better than that of an individual parameter (P < 0.05).ConclusionIVIM-MRI parameters provided information about the microstructure and microcirculation of regional LNs in rectal cancer, also improved diagnostic performance in identifying metastatic LNs.

Research on Solar Power Generation Disaster Relief Tent Based on Inflatable Structure

The local structure of disaster relief tent was analyzed by ANSYS. The deformation of inflatable column was basically consistent with the deformation of inflatable column after expansion, and the stress at different positions was also consistent with the basic size. The optimum ratio of height to width of arch was obtained to ensure the strength and stability of arch. At the same time, the optimal ratio of long axis to short axis of ellipse with small stress and strain was obtained. The suitable size was chosen to design the overall structure of the inflatable tent. The practical number and distribution mode of solar energy film was formulated, and the solar energy film was combined with tent. Finally, the inflatable structure tent with power generation function for disaster areas was obtained.

The effect of particle shape in particle detection using inductive sensors

Inductance sensor is one of the commonly used methods in the detection of oil metal particles. The shapes of particles are different, caused by the different forms of wear in oil; however, the effect of particle shapes on the inductive sensors was not under consideration. In order to obtain more accurate measurement results of inductive sensors in metal particle detection and other areas of application, the effect of particle shapes on an inductive sensor is studied in this paper. The inductance change of coil about the ratio of long axis to short axis of particles is obtained in accordance with the experimental validation depending on the cylindrical particles. The results show that the inductance changes are 0.25 nH, 0.32 nH, and 0.92 nH with the ratios of long axis to short axis of particles l/d are 0.67, 1, and 3 with the same volume. It is observed that the inductance change of coil ΔL increases with an increasing ratio of long axis to short axis of particles l/d, which provides a theoretical basis for inductive sensors in metal particle detection and other areas of application.

3D reconstitution and numerical analysis of superelastic behavior of porous shape memory alloy

In this work, a CAD 3D foam structure of Ni-Ti Shape Memory Alloy (SMA) is rebuilt using ellipsoid unit cells in order to study the superelastic behavior of porous SMAs. A taking and placing algorithm based on a uniform and a normal distributions is adopted for the 3D reconstitution process. In the design sample, dimensions, positions and orientations of the ellipsoid unit cells are randomly selected. A SMA constitutive model including phase transformation, martensitic reorientation and twins accommodation is selected to simulate the superelastic behavior of the SMA foam. As an application, the compression of SMA porous sample with random ellipsoid unit cell distribution is simulated by finite element in order to show the efficiency of the proposed methodology to predict its superelastic response and to analyze the porosity effect. The obtained results show that the force-displacement or stress-strain responses of the porous material are highly depend on the foam porosity. The effects of porosity, size, orientation, ratio of long axis and short axis, and distribution of unit cell on the superelastic behavior of SMA porous material are also discussed in both closed cells and open cells cases.

RF25 HYBRID PALLIATION ALLOWS THE HYPOPLASTIC LEFT VENTRICLE FOR A CHANCE OF BIVENTRICULAR REPAIR: ECHO-SURVEILLANCE ON LEFT HEART GROWTH

Background: Several parameters of LV adequacy are available, however, it is now clear that the timing of decision plays a crucial role in the fate of the borderline LV, because the longer the ventricle is allowed to grow, the higher the probability to achieve functional independence. Aim of the study: Our aim is to describe the growth potential of borderline left ventricles after pulmonary arteries banding (PAB) and arterial duct stenting (ADS). Methods: 44 patients (mean weight 3 Kg, from 1,9 to 4,2 Kg), who were born with different hypoplastic LV variants underwent hybrid palliation at 3,6 days (1 to 7) in our institution between October 2011 and January 2018. We divided 36 patients into 3 groups according to the severity of LV hypoplasia: 14 pts with MA or MS and AoA, who are not supposed to show any growth of LH structures over time, 6 pts with IAoA and VSD whose LV is usually suitable for biventricular repair, and 16 pts with intermediate features. The latter group included pts with MS/AS, right unbalanced AVSD or Shone complex, all of them with severely underdeveloped LV, expressed by LV mass below -2 Z scores. Among this 16 pts we further distinguished three subgroups, according to the subsequent surgical treatment they underwent after the interstage period and potential LV growth: group 1 had single ventricle staged palliation (5 patients), group 2 biventricular repair (8 patients) and group 3 early death occurrence (3 patients). Two-dimensional echocardiograms of patients from group 1 and 2 were retrospectively reviewed, comparing examination recorded at birth with those obtained 4 months after hybrid palliation. Results: Aortic annulus, aortic root, mitral and tricuspid annulus, LV systolic and diastolic dimension, systo-diastolic volumes and mass, LV long-axis to heart long-axis ratio (LAR), transverse and distal arch and aortic isthmus diameters were used. LV mass and volumes are critically small in both groups at birth. Although a trend towards growth can be seen for almost all the analyzed parameters, a significant change of LV mass and volumes from pre- to post-hybrid procedure is evident in group 2, which is absent in group 1. Conversely, parameters like aortic annulus, aortic root and LAR in group 1, already at birth, were significantly smaller than they were in group 2. Conclusion: The goal in the treatment of borderline LV is to postpone the decision until the time LV has fully expressed its growth potential: then, many more biventricular repairs will be reached than at the time of first evaluation.

Radiographic Assessment of the Popliteal Lymph Node to Aid the Differentiation of Canine Stifle Osteosarcoma From Moderate to Severe Stifle Degenerative Joint Disease

Degenerative joint disease of the stifle is a common canine osseous pathology. Early degenerative changes may show mild mineral proliferation of periarticular margins with soft tissue, resulting in joint distension. If the joint is chronically unstable, osseous changes become more complex. Moderate to severe stifle degenerative disease then transitions to a combination of bony proliferation and resorption as subchondral cystic changes develop. The radiographic descriptions of moderate to severe degenerative disease overlap with those of subtle aggressive disease. If this occurs in a location prone to primary bone tumors, like the distal femur, radiographic interpretation becomes difficult. The aim of this study was to evaluate the utility of objectively assessing the popliteal lymph node size and shape on radiographs to differentiate moderate to severe stifle degenerative joint disease from distal femoral or tibial osteosarcoma. Stifle radiographs were acquired for evaluation of pelvic lameness localized to the stifle joint. Dogs with moderate to severe degenerative stifle joint disease were radiographed at 3 time points: prior to surgery for a tibial plateau leveling osteotomy (103), immediately postoperation (103), and at a recheck 6-8 weeks postsurgery (62). Dogs with osteosarcoma were radiographed only at time of diagnosis (42). Length and width gross popliteal lymph node measurements and a ratio of long axis to short axis were compared between groups using nonparametric analysis. No significant difference was determined using a long axis to short axis ratio for the popliteal lymph node to differentiate moderate to severe stifle degenerative joint disease and osteosarcoma (P = .290). The gross measurements of the long axis and short axis of the popliteal lymph node for dogs with osteosarcoma were significantly greater than the degenerative joint disease groups (P = .017, P = .000). Thus, evaluation of a long axis to short axis ratio for popliteal lymph nodes does not provide a clinically useful objective measure in differentiating peristifle osteosarcoma from moderate to severe degenerative disease of the stifle joint. The length and width of the popliteal lymph node differed significantly; however, the clinical difference is minimal.

Value of multi-slice spiral CT image texture analysis in diagnosing lymphatic metastasis of rectal cancer

Objective To investigate the value of multi-slice spiral CT image texture analysis in differentiating metastatic (MLN) from non-metastatic lymph nodes (NLN) in patients with rectal cancer. Methods Thirty five patients with rectal cancer who were pathologically confirmed by total mesorectum excision were included retrospectively, with regional lymph nodes (short-axis diameter of larger than 3 mm) found in preoperative CT images. All the patients underwent preoperative abdominal and pelvic dynamic contrast-enhanced CT scan. Regional lymph nodes were identified according to pathological findings, and were divided into MLN and NLN groups. The short-axis diameter, short-to long-axis diameter ratio of lymph nodes were manually measured and calculated, and the texture features, including skewness, kurtosis, variance, entropy and inverse difference moment, were analyzed. The above parameters between MLN and NLN groups were compared using independent sample t test or Mann-Whitney U test. ROC curve analysis was performed regarding the statistically significant parameters and the areas under curve (AUC) were calculated. Multivariate Logistic regression analysis was accomplished to obtain the independent predictive factor of diagnosing regional lymph nodes. Results A total of 68 regional lymph nodes were obtained and consisted of 31 MLNs and 37 NLNs. The short-axis diameter, kurtosis, and entropy of the MLN group were significantly higher than those of the NLN group (all P 0.05). The AUC for distinguishing MLN from NLN of the short-axis diameter, kurtosis and entropy were 0.79, 0.67, and 0.85, respectively. Multivariate logistic regression analysis showed that only entropy (odds ratio= 8.48, 95% confidence interval was 3.01 to 23.92, P<0.01) was screened out as the independent variable, which suggested that the entropy was the unique predictor for characterizing regional lymph nodes of rectal cancer. Conclusion Multi-slice spiral CT images texture analysis can facilitate the accurate differentiation between MLN and NLN in patients with rectal cancer, and especially the entropy has the optimal reference significance. Key words: Rectal neoplasms; Lymphatic metastasis; Tomography, X-ray computed; Texture analysis

Endothelial Cell Mechanical Responses Are Dependent on Both Fluid Shear Stress and Tensile Strain

Vascular endothelial cells are sensitive to their mechanical environment. They are regularly subject to both fluid shear stress as a result of blood flow, as well as cyclic tensile (or compression) strain due to blood vessel dilation (or contraction). The purpose of this study was to characterize physiological responses and morphological changes occurring in vascular endothelial cells when they were exposed to altered mechanical loadings, i.e., fluid shear stress and/or tensile strain. Human coronary artery endothelial cells (HCAEC) were grown to confluence in a 6‐well Flexcell plate coated with fibronectin. Cells were then placed in a programmable shearing and stretching device, where they were exposed to dynamic shear stress and cyclic tensile strain simultaneously at physiological or pathological levels. Three shear stress‐tensile strain conditions were used: 1) shear stress at 1 Pa and cyclic tensile strain at 7%, mimicking normal mechanical loading conditions in a healthy coronary artery; 2) shear stress at 3.7 Pa and tensile strain at 3%, mimicking pathological shear stress/strain conditions occurring at the stenosis (60%) throat in a diseased coronary artery; 3) shear stress at 0.7 Pa and tensile strain at 5%, mimicking pathological shear stress/strain conditions in the recirculation zones downstream of a stenosis. Following 1‐hour shear stress‐strain treatment, cells were fixed and cytoskeletal F‐actin filaments were stained using FITC conjugated phalloidin. Cell morphology was visualized using immunofluorescence microscope; cell area and elongation (ratio of long axis over short axis) were quantified using the Image J software. Under all conditions, cells that were exposed to shear stress and cyclic tensile strain concurrently were much larger compared to untreated cells or cells that were exposed to either shear stress or tensile strain alone. Stenosis conditions caused a significant increase in cell area compared to the other two conditions (normal and recirculation). In contrast, cell elongation decreased significantly under concurrent shear stress and tensile strain, with the lowest values observed under recirculation conditions. PECAM‐1 phosphorylation, an indicator of mechanotransduction pathway activation, was also measured, using a solid phase ELISA approach. The results demonstrated that the simultaneous stimulation from shear stress and tensile strain induced significant changes in endothelial cell surface phosphorylated PECAM‐1 expression, compared to when cells were exposed to only shear stress or tensile strain. These findings indicated the complex interplay between altered flow‐induced shear stress and tensile strain could significantly affect vascular endothelial cell responses. Therefore, to better understand how mechanical conditions affect endothelial cell mechanotransduction and functions, both shear stress and tensile strain need to be considered.

Particle capture efficiency of elliptic cylinder matrices for high-gradient magnetic separation

ABSTRACTHigh-gradient magnetic separation (HGMS) is an effective method to recover fine weakly magnetic minerals or remove ferromagnetic and paramagnetic particles from aqueous solution. The most commonly used matrices are circular cylinders of high magnetic permeability. However, special cross-section matrices may present better magnetic characteristics and improve the separation efficiency. In this paper, the magnetic field and flow field characteristics of elliptic cross-section matrix were studied in the elliptic coordinate system. The particle capture of the elliptic matrix in the longitudinal configuration of HGMS was modelled and the motion equations of the magnetic particles were derived. The particle capture radius and efficiency were calculated and were compared with those of the circular matrix. Two circumstances were considered to investigate the particle capture of elliptic matrix: the short axis of the elliptic matrix is equal to the diameter of the circular matrix and the cross-section area of the elliptic matrix is equal to that of the circular matrix. The influence of λ (ratio of long axis to short axis) of the elliptic matrix on the capture efficiency of micron-sized paramagnetic particles in the two circumstances was also studied. The results showed that for all the conditions considered, there exists an optimum λ at which the particle capture efficiency reaches the maximum. With the matrices of the optimum λ and suitable d values, the capture efficiency of the 10 μm and 2 μm haematite particles can be improved by 6 ~ 22% and 1 ~ 3% compared with the circular matrices, respectively. Both approaches can be adopted to utilize elliptic matrices in HGMS to improve the particle capture efficiency. The results reveal the higher particle capture efficiency of the elliptic matrix and its application possibility in HGMS.

Impact of endoscopic ultrasound-guided fine needle aspiration of small lymph nodes

Abstract Background: There is very limited literature on results of fine needle aspiration (FNA) of small (defined as ≤1 cm at long and short axis) lymph nodes, particularly in the setting of pyrexia of unknown origin (PUO). Methods: The study was conducted from July 2014 to December 2015 at a tertiary care center. A total of 34 endoscopic ultrasound (EUS)-guided FNAs in 33 patients were done for lymph nodes ≤1 cm at long and short axis and these were included in the analysis. Results: The study cohort comprised 33 patients; 23 males and 10 females, mean age of 58 ± 12 years. Indication of FNA was to look for malignancy (n = 15), PUO (n = 16), unexplained weight loss (n = 1), and presence of lymphadenopathy in prospective liver donor (n = 1). The FNA was taken from mediastinal nodes (n = 20, 14 subcarinal) and abdominal (n = 14, 8 at porta). The mean size of lymph nodes was 87 ± 11 mm at large axis and 68 ± 17 mm at short axis. A total of 3 (8.8%) FNAs were nondiagnostic (inadequate material). The cytopathologic diagnosis was malignancy in 8 (23.5%), granulomatous change in 8 (23.5%), and reactive lymphadenopathy in 15 (44.1%). Thus, EUS-guided FNA of these small nodes changed the management decisions in 44% of cases (one patient had tubercular lymphadenopathy at two sites). The 22-gauge EUS FNA needle was used in majority of patients (n = 26). There was no significant difference between pathologic (malignant and granulomatous) and reactive lymph nodes regarding size at long or short axis, ratio of long and short axis, hypoechogenicity, and sharply defined borders. Conclusion: EUS-guided FNA of small lymph nodes showed pathological enlargement in 44% of cases.