Progress of bile fluid dynamics in the mechanism of hepatic bile duct stone formation / 中华肝胆外科杂志

Hepatolithiasis is a common disease in hepatobiliary surgery. The changes of bile dynamics in the biliary system, such as flow rate, pressure, viscosity, etc., play an important role in stone formation. In this paper, we introduce the bile fluid dynamics of the biliary system, analyze the influencing factors of bile dynamics change, the relationship between bile dynamics change and calculus, and the application of bile fluid dynamics in the treatment of hepatolithiasis, providing ideas and basis for the prevention and treatment of hepatolithiasis.

Aquatic resistance training repercussions on the dynamic stability in volleyball athletes / Repercussões do treino de resistência aquático sobre a estabilidade dinâmica dos atletas de vôlei / Repercusiones del entrenamiento de resistencia acuática en la estabilidad dinámica de los atletas de voleibol

ABSTRACT Introduction Resistance training is considered a practical pathway for increasing strength and speed. Objective Explore the aquatic resistance training on the dynamic stability in volleyball athletes. Methods Using aquatic resistance training reinforcement, 20 first-level national male volleyball athletes were randomly divided into control and experimental groups. The time of the experiment was ten weeks. In the end, lower limb muscle strength, jumping ability, dynamic stability, and muscle pain were compared. Residual effects were also checked six weeks after the end of the experiment. Results The aquatic resistance training group stopped training for six weeks, peak torque at 60°/s, 180°s of relative knee extension, jump height, full arm swing, and all three phases of the high jump were significantly better than the preliminary test; water entry speed in the vertical direction was also significantly better one week after training. Conclusion Aquatic resistance training can significantly improve the dynamic stability of the lower limbs, and its effect can be maintained up to 6 weeks after completion. It is recommended to apply resistance enhancement training to maintain fitness, especially for long periods. Evidence Level II; Therapeutic Studies - Investigating the result.

RESUMO Introdução O treino de resistência é considerado um meio eficaz para aumento de força e a velocidade. Objetivo Explorar as repercussões do treino de resistência aquática sobre a estabilidade dinâmica dos atletas de vôlei. Métodos 20 atletas de primeiro nível nacionais de vôlei masculino, foram divididos aleatoriamente em um grupo de treinamento para controle e outro grupo experimental com reforço utilizando treino de resistência aquático. O tempo do experimento foi de 10 semanas. Ao final, foram comparadas força muscular do membro inferior, capacidade de salto, estabilidade dinâmica, dor muscular. Foram verificados também os efeitos residuais em seis semanas após o término do experimento. Resultados O grupo de treino de resistência aquática parou de treinar por 6 semanas, com pico de torque a 60°/s, 180°s de extensão relativa do joelho, a altura de salto, o balanço completo dos braços e as três fases do salto em altura foram significativamente melhores do que o teste primário; a velocidade de entrada na água na direção vertical também foi significativamente melhor uma semana após o treinamento. Conclusão O treino de resistência aquático pode melhorar significativamente a estabilidade dinâmica dos membros inferiores e seu efeito pode ser mantido até 6 semanas após o término. Recomenda-se aplicar o treino de aprimoramento da resistência para manter o condicionamento físico, especialmente por longos períodos. Nível de evidência II; Estudos Terapêuticos - Investigação de Resultados.

RESUMEN Introducción El entrenamiento de resistencia se considera una forma eficaz de aumentar la fuerza y la velocidad. Objetivo Explorar las repercusiones del entrenamiento de resistencia acuática en la estabilidad dinámica de los atletas de voleibol. Métodos 20 atletas masculinos de voleibol de primer nivel nacional, fueron divididos aleatoriamente en un grupo de entrenamiento de control y otro grupo experimental con refuerzo mediante entrenamiento de resistencia acuática. El tiempo del experimento fue de 10 semanas. Al final, se comparó la fuerza muscular de las extremidades inferiores, la capacidad de salto, la estabilidad dinámica y el dolor muscular. También se comprobaron los efectos residuales a las seis semanas de finalizar el experimento. Resultados El grupo de entrenamiento de resistencia acuática dejó de entrenar durante 6 semanas, el pico máximo de torque a 60°/s, la extensión relativa de la rodilla a 180°s, la altura del salto, el balanceo completo del brazo y las tres fases del salto de altura fueron significativamente mejores que en la prueba primaria; la velocidad de entrada al agua en la dirección vertical también fue significativamente mejor una semana después del entrenamiento. Conclusión El entrenamiento de resistencia acuática puede mejorar significativamente la estabilidad dinámica de los miembros inferiores y su efecto puede mantenerse hasta 6 semanas después de su realización. Se recomienda aplicar un entrenamiento de mejora de la resistencia para mantener la forma física, especialmente durante largos periodos. Nivel de evidencia II; Estudios terapéuticos - Investigación de resultados.

Cine phase-contrast magnetic resonance imaging evaluation of cerebrospinal fluid flow dynamics in healthy pediatric subjects / Avaliação da dinâmica do fluxo do líquido cerebrospinal por cine-ressonância magnética com contraste de fase em crianças saudáveis

Abstract Objective: To evaluate cerebrospinal fluid dynamics, using cine phase-contrast magnetic resonance imaging (cine-PC MRI), in healthy pediatric subjects, determining the normal flow values in this population, as well as identifying differences related to age, sex, and body surface area. Materials and Methods: This was a descriptive cross-sectional study involving 32 healthy children and adolescents, in whom the flow of cerebrospinal fluid through the cerebral aqueduct was evaluated quantitatively with cine-PC MRI. We used specialized software to analyze the images obtained with cine-PC MRI, drawing a region of interest on the aqueduct. A flow-time curve was obtained, as were automated measurements of the various parameters. Results: The following normal (mean) values were obtained: net flow, 1.10 ± 0.99 mL/m; stroke volume, 12.2 ± 10.1 μL/cycle; mean velocity, 0.72 ± 1.00 cm/s; peak systolic velocity, 5.28 ± 2.30 cm/s; peak diastolic velocity, 4.51 ± 1.77 cm/s. These values were not affected by age or sex. In addition, body surface area was not found to correlate significantly with mean velocity or stroke volume. Conclusion: In children and adolescents, the basic cerebrospinal fluid flow parameters, as determined by cine-PC MRI, appear to be independent of age and sex.

Resumo Objetivo: Avaliar a dinâmica do fluxo do líquido cerebrospinal por cine-ressonância magnética com contraste de fase em crianças saudáveis, para determinar os valores normais de fluxo nesta população, bem como a diferença entre medições distintas de acordo com idade, sexo ou área da superfície corporal. Materiais e Métodos: Convocamos 32 crianças saudáveis em uma análise descritiva de prevalência para a avaliação quantitativa do fluxo do líquido cerebrospinal pelo aqueduto de Sylvius. A análise foi realizada por meio de software especializado, desenhando uma região de interesse no aqueduto. Uma curva de fluxo-tempo e medições automáticas de diversos parâmetros foram obtidas. Resultados: Os seguintes valores normais foram obtidos: fluxo efetivo de 1,10 ± 0,99 mL/m; volume médio de 12,2 ± 10,1 μL/ciclo; velocidade média de 0,72 ± 1,00 cm/s; pico de velocidade sistólica de 5,28 ± 2,30 cm/s; pico de velocidade diastólica de 4,51 ± 1,77 cm/s. Esses valores não foram afetados pela idade ou sexo das crianças. Além disso, não foi encontrada correlação significativa entre a área corporal, a velocidade média e o volume sistólico. Conclusão: De modo geral, os parâmetros básicos do fluxo do líquido cerebrospinal independem de idade e sexo em crianças.

Hemodynamic abnormality in patients with primary trigeminal neuralgia / 中华神经科杂志

Objective:To investigate specificity of neurovascular compression in patients with primary trigeminal neuralgia (PTN) by three-dimension reconstruction and computational fluid dynamics.Methods:Clinical characteristics and preoperative magnetic resonance imaging (MRI) data of 20 patients with both PTN and single artery compression (PTN group) and 10 patients without PTN but having neurovascular contact in MRI images (control group) in the Second Affiliated Hospital of Zhengzhou University from January 2018 to December 2019 were collected and analyzed. After three-dimension reconstruction of the MRI images, curvature of the arterial loop, angle between the plane of arterial loop and the trigeminal nerve and location of the compression were observed. Then bidirectional structure-fluid coupling based on the optimized stereolithography models of arterial loop and nerve were processed by ANSYS 19.2 software. In the location of the compression of contact, equivalent stress (ES) of arterial loop on the nerve, shearing stress (SS) of the blood flow and local deformation of the nerve were iteratively computed. All parameters were analyzed and compared between the PTN group and the control group, and the correlation analysis was proceeded between the anatomical parameters and hemodynamical parameters.Results:The curvature of arterial loop [0.21(0.12) mm -1vs 0.13(0.07) mm -1, U=34.00, P<0.05], the angle between vascular loop and nerve [69.70(30.67)° vs 43.40(37.21)°, U=38.00, P<0.05] in the PTN group were significantly greater than those in the control group, and the location of compression was significantly closer to the root of nerve in the PTN group [PTN group: (4.23±1.29) mm vs control group: (5.54±1.85) mm, t=-2.26, P<0.05]. The average SS [15 952.48(5 365.56) Pa vs 12 501.97(6 355.26) Pa, U=53.00, P<0.05], ES [24 965.65(7 693.22) Pa vs 14 992.99(9 824.08) Pa, U=32.00, P<0.05] in the PTN group were significantly greater than those in the control group. The curvature of arterial loop was positively correlated with the SS ( r=0.931, P<0.05) and ES ( r=0.962, P<0.05), and the latter two ( r=0.787, P<0.05; r=0.853, P<0.05) were positively correlated with the local neural deformation. Conclusions:In patients with PTN, offending artery compresses the root of nerve by greater arterial curvature and angle between the arterial loop and nerve. These anatomical differences will cause significantly greater SS, ES and local neural deformation.

Mitral valve-in-valve: defining the indication limits by in vitro hydrodynamic tests in a brazilian transcatheter prosthesis

Abstract Introduction: Reoperations in cardiac surgery represent a clinical challenge, particularly because of the higher rate of perioperative morbidity and mortality. Mitral valve reoperation owing to bioprosthesis dysfunction, transcatheter treatment with a prosthesis implantation over the prosthesis has emerged as an alternative, especially for patients with a previous approach. In this study, we analyzed the hydrodynamic behavior of transcatheter prosthesis implantation in conventional mitral bioprostheses through hydrodynamic tests and produced a recommendation for the size of transcatheter valve most adequate for valve-in-valve procedure. Methods: Mitral bioprostheses were attached to a flow duplicator and different combinations of transcatheter prostheses were implanted inside. The equipment simulates the hydrodynamic behavior of the valves submitted in vitro and determines transvalvular pressures and flow parameters. Results: All tests could be performed. Better hydrodynamic performance occurred for transcatheter prostheses 1 mm smaller than bioprostheses, except for the 27-mm bioprostheses. Effective valve areas (cm²) and transvalvular gradients (mmHg) were, respectively: Bioprosthesis × Inovare: 27 × 28 mm: 1.65 and 5.95/29 × 28 mm and 31 × 30 mm: 2.15 and 3.6. Conclusion: The mitral valve-in-valve implantation proved to be feasible in vitro. The use of 27-mm bioprostheses should be judicious, with preference for a 26-mm transcatheter valve. In the 29 and 31-mm bioprostheses, the implantation was very satisfactory, with good effective valve areas and transvalvular gradients, with preference for smaller transcatheter valves.

Microsurgical Cisternostomy for Treating Critical Patients with Traumatic Brain Injury - An alternative Therapeutic Approach

Introduction Traumatic brain injury (TBI) is a major cause of mortality around the world. Few advances regarding surgical approaches have been made in the past few years to improve its outcomes. Microsurgical cisternostomy is a well-established technique used in vascular and skull base surgery and recently emerges as a suitable procedure with lesser costs and morbidity when compared with decompressive craniectomy in patients with diffuse TBI. This study aims to describe the technique, indications, and limitations of cisternostomy and to compare it with decompressive craniectomy (DC). Methods A prospective study is being conducted after obtaining approval of the local human ethics research committee. Once the inclusion and exclusion criteria are applied, the patients are submitted to microsurgical cisternostomy, pre and postoperative neurological status and brain computed tomography (CT) evaluation. A detailed review was also performed, which discusses diffuse TBI, DC, and cisternostomy for the treatment of TBI. Results Two patients were submitted to cisternostomy after TBI and the presence of acute subdural hematoma and hugemidline shift at admission computed tomography. The surgery was authorized by the family (the informed consent form was signed). Both patients evolved with a good recovery after the procedure, and had a satisfactory control brain CT. No further surgeries were required after the initial cisternostomy. Conclusions Cisternostomy is an adequate technique for the treatment of selected patients affected by diffuse TBI, and it is a proper alternative to DC with lesser costs and morbidity, since a single neurosurgical procedure is performed. A prospective study is being conducted for a better evaluation and these were the initial cases of this new protocol.

Comportamento hidrodinâmico de sistemas alagados construídos de escoamento horizontal subsuperficial de diferentes proporções geométricas e tempos de operação / Hydrodynamic behavior of horizontal subsurface flow constructed wetlands with different aspect ratio and operation time

RESUMO No presente trabalho, teve-se por objetivo avaliar a influência da proporção geométrica e o tempo de operação na hidrodinâmica do sistema. Para isso, três sistemas alagados construídos de escoamento horizontal subsuperficial (SACs-EHSS) de diferentes razões comprimento:largura (L/B) foram caracterizados no que se refere ao comportamento hidrodinâmico, no início e após três meses de sua operação, durante o tratamento de esgoto sanitário. O comportamento hidrodinâmico foi avaliado por meio da técnica estímulo-resposta, com a injeção de traçador de cloreto de lítio (LiCl), na forma de pulso, e da construção da curva de distribuição dos tempos de residência (DTR), a partir da qual foram extraídos parâmetros que permitiram a análise hidrodinâmica dos sistemas. Verificou-se que todos os SACs-EHSS apresentaram comportamento hidrodinâmico do tipo disperso, embora tenha sido observada correlação inversa entre L/B e o número de dispersão (d) no sistema. O tempo de operação desses sistemas também proporcionou pequena redução no d, em todos os SACs-EHSS.

ABSTRACT The objective of the present work was to evaluate the geometric ratio and the operating time's influence on the systems' hydrodynamic conditions. For this purpose, three horizontal subsurface flow constructed wetlands (HSSF-CWs) in pilot scale, with same useful volume () but with different length:width (L/B) ratio, were characterized regarding the hydrodynamic behavior at the beginning and after 3 months of operation, in sewage treatment. To obtain the HSSF-CW conditions, the stimulus-response technique with the lithium chloride (LiCl) tracer injection on a pulse format was used. Thus, the residence time distribution curve was constructed, from which parameters were extracted and enabled the hydrodynamic analysis of the systems. It was found that all HSSF-CWs presented dispersed hydrodynamic behavior, although the results indicated an inverse correlation between L/B and the dispersion number. The operating time of these systems provided a reduction in the dispersion number in all HSSF-CWs, different from the results found in some works.

Effect of anatomical changes of frontal recess and frontal sinus on airflow after nasalisation by image reconstruction and numerical simulation / 中华耳鼻咽喉头颈外科杂志

Objective@#To describe the influence of post-operative anatomical structure changes on nasal airflow characteristics by 3D reconstruction and numerical simulation in real cases after nasalisation with Draf Ⅲ so as to explore the correlation between the changes of anatomical structure and subjective symptoms as well as airflow characteristics.@*Methods@#Ten patients underwent nasalization with Draf Ⅲ in Department of Rhinology in Beijing Tongren Hospital from 2006 to 2018 were selected retrospectively. Postoperative follow-up of all patients was more than 1 year. All patients had no abnormalities in their paranasal sinus CT scans and Lund-Kennedy scores were 0 except scar. VAS scores including nasal obstruction, stimulation in frontal sinus, and headache were collected at the same period. The control model was a normal person. Numerical simulation was used for calculating airflow characteristics in deep inspiratory period of both models. Independent sample Mann-Whitney U test and Spearman correlation test were used by software SPSS 22.0.@*Results@#The airflow pressure in frontal sinus ostium was (7.21±1.39)×104 Pa (Mean±SD), which was lower than that in normal subjects (8.99×104 Pa) under deep inspiratory simulation. But, the velocities in frontal sinus ostium and frontal sinus were (40.10±2.46) m/s and (28.19±1.73) m/s respectively, which were higher than those in normal one (2.70 m/s, 0.73 m/s). The airflow patterns of the two models were basically similar. There was no significant difference in the opening size and volume of frontal sinus between different groups after grouped by three symptoms respectively. No correlation could be found between the opening size and volume of the frontal sinus with the appearance and severity of three subjective symptoms.@*Conclusions@#The airflow pattern and distribution after nasalisation with Draf Ⅲ are like those of normal person. There is no correlation between the changes of anatomy in frontal recess and frontal sinus and nasal airflow characteristics as well as subjective symptoms.

Analysis of causes for non-stone parotid obstructions / 口腔疾病防治

@#Parotid obstructions can cause repeated swelling of the glands. Previously, duct stones were thought to be the main cause of obstructions, but salivary gland endoscopy examinations have revealed the absence of stones or foreign bodies in the duct system of the parotid glands with obstructive symptoms. Diseases of the parotid gland with obstructive symptoms include chronic recurrent parotitis, non-stone chronic obstructive parotitis, Sjögren′s syndrome, IgG4-related parotitis and radiation-induced parotitis. The mechanism of obstructions is unknown, and the disease course is prolonged. In this paper, based on a brief analysis of duct stenosis, distortion and mucus emboli, which may lead to parotid obstructions, a new perspective is emphasized: the duct system of the parotid and flowing saliva constitute a microflow field. Based on the principle of fluid mechanics, the flow of saliva in the flow field can be affected by the confluence, diameter changes, and twist of the ducts. This outcome results in changes in the low velocity zone, backflow, counterflow and turbulence; affects saliva flow and normal discharge; and causes symptoms of parotid obstruction. An analysis of the possible mechanisms of parotid obstruction using two variables, duct anatomy and saliva traits, helps explain the causes of nonstone parotid obstructions.

Effect of incisor retraction on three-dimensional morphology of upper airway and fluid dynamics in adult class Ⅰ patients with bimaxillary protrusion / 中华口腔医学杂志

Objective@#To investigate the effect of incisor retraction on three-dimensional morphology of upper airway and fluid dynamics in class Ⅰ adult patients with bimaxillary protrusion.@*Methods@#Thirty class Ⅰ patients with bimaxillary protrusion that received fixed orthodontic treatment in Department of Stomatology, The First Affiliated Hospital of Wenzhou Medical University from January 2011 to September 2014 were selected using random number table. All the patients were treated with extraction of four first premolars and retraction of anterior teeth using implant anchorage. Cone-beam CT (CBCT) scans were performed before and after incisor retraction for all patients. The CBCT data of the upper airway were constructed using Mimics 16.0, and the flow field characteristics inside the upper airway were simulated using Ansys 14.0. The changes of volume (V), mean cross-sectional area (mCSA), maximum lateral diameters/maximum anteroposterior diameters (LP/AP) of cross section, the maximum pressure of airflow (Pmax), the minimum pressure of airflow (Pmin) and pressure drop (△P) of nasopharynx, oropharynx and hypopharynx before and after incisor retraction were measured and compared using paired t test. The correlation between the variation of △P in the most significant pharyngeal part and the morphological variables after incisor retraction was analyzed using Pearson correlation test.@*Results@#No statistical differences were observed in the morphology and flow field in nasopharynx before and after incisor retraction (P>0.05). Before incisor retraction, the oropharyngeal volume and mCSA were (7 580±622) mm3 and (217±40) mm2, respectively, and the hypopharyngeal volume and mCSA were (2 564±162) mm3, and (239±43) mm2, respectively. After incisor retraction, the volumes of oropharynx and hypopharynx were (6 885±601) mm3 and (2 535±156) mm3, respectively, and mCSA of oropharynx and hypopharynx were (197±37) mm2 and (236±42) mm2, respectively. The volume and mCSA of oropharynx and hypopharynx were significantly decreased after incisor retraction (P<0.05). The greatest changes in pharyngeal volume and mCSA occurred in the oropharynx. In addition, the LP/AP of oropharynx after incisor retraction was changed from 1.9±0.6 to 2.1±0.7, which was significantly increased compared with the levels before incisor retraction (P<0.05). After simulation of pharyngeal airflow, the oropharyngeal Pmin, hypopharyngeal Pmax and Pmin were (-13.7±4.3), (-8.3±3.8) and (-42.8±9.5) Pa, respectively, whereas the values turned to (-16.4±6.5), (-11.9±3.6) and (-46.0±11.0) Pa, respectively after incisor retraction, which was significantly reduced (P<0.05). △P of oropharynx was significantly increased from (42.7±10.1) Pa to (45.2±13.0) Pa after incisor retraction (P<0.05) and the variation of oropharyngeal △P was negatively correlated with the variation of V and mCSA in oropharynx before and after incisor retraction (r=-0.681, P=0.001; r=-0.844, P=0.000).@*Conclusions@#The oropharynx was constricted and the pharyngeal resistance was increased after incisor retraction in adult class Ⅰ patients with bimaxillary protrusion. A comprehensive and systematic evaluation of the pharyngeal morphology and ventilatory function were very important for making a scientific and rational clinical treatment plan.

Estudos hidrodinâmicos do escoamento em caixa de gordura empregada no tratamento preliminar dos efluentes de cozinha industrial / Hydrodynamic flow studies in the grease trap employed in the primary treatment of effluents from industrial kitchen

RESUMO Efluentes de cozinhas industriais se caracterizam pela geração de elevado teor de óleos e gorduras. Esses produtos notadamente causam sérios problemas ambientais, sendo obrigatória a instalação de unidades de pré-tratamento no local onde são gerados, e com isso surge a importância das caixas de gordura (CGs), destinadas a esse fim. O desempenho das CGs tem relação direta com as condições processuais e hidrodinâmicas que ocorrem em seu interior. O presente estudo teve o objetivo de comparar as características hidrodinâmicas da CG funcionando sob duas condições operacionais distintas: flotação gravitacional e flotação forçada (auxiliada por difusores de ar). Realizaram-se quatro testes hidrodinâmicos na CG, sendo o primeiro e segundo testes com água limpa a uma vazão constante e o terceiro e quarto testes com efluente do Restaurante Universitário (RU), cuja vazão era variável em função das atividades do RU. Aplicaram-se a metodologia de distribuição do tempo de residência (DTR) e a técnica de estímulo e resposta utilizando cloreto de potássio (KCL) como elemento traçador. Os resultados hidrodinâmicos no primeiro teste operacional apontaram características entre o escoamento pistonado e o escoamento dispersivo, com moderada intensidade de dispersão e certa mistura. O segundo teste, com aeração, mostrou tendência ao escoamento em mistura completa com grande intensidade de dispersão. O terceiro teste, por flotação gravitacional, mostrou tendência a fluxo pistonado, enquanto o quarto teste demonstrou fluxo dispersivo, tendendo a um elevado grau de mistura. Observaram-se, em todos os testes, aparentes desvios causados provavelmente por zonas estagnadas (mortas), curtos-circuitos e fenômenos de recirculação, fazendo com que o volume útil da CG não fosse plenamente utilizado. Apesar de não fazer parte do escopo deste trabalho, a eficiência na remoção de óleos e graxas foi maior quando aplicada a flotação gravitacional, cuja mistura tende à pistonada, o que auxilia o grau de aquiescência e permite maior acúmulo de gordura flotada. Quanto à flotação forçada por meio dos aeradores, grande parte da gordura é oxidada e, portanto, minimizada, formando uma escuma de cor clara (branca) e de baixíssima espessura na parte superior da CG. Todavia, por se tratar de elevado grau de mistura, a eficiência de retenção se mostrou, como previsto, inferior ao processo gravitacional.

ABSTRACT Effluents from industrial kitchens are characterized by high-generated content of oils and fats. These products cause serious environmental problems, and it is mandatory to install pretreatment units in the places where they are generated. Hence the importance of grease traps, intended for this purpose, whose performance is directly related to the processual and hydrodynamic conditions inside. This study aimed to compare the hydrodynamic characteristics of greaser trap (GT) working under two different operating conditions: gravitational flotation and forced flotation (aided by air diffusers). Four hydrodynamic tests were performed in the GT, the 1st and 2nd tests with clean water at a constant flow rate and the 3rd and 4th tests with wastewater from the university restaurant, with variable flow. The methodology applied to evaluate the residence time distribution (RTD) was the technique of stimulus/response using potassium chloride (KCl) as a tracer element. The hydrodynamic results in the 1st operating test indicated features between slug flow and dispersive flow, with moderate dispersion intensity and some mixing. The 2nd operating test, under aeration, showed tendency of complete mixing with great dispersion intensity. The 3rd test, by gravitational flotation, tended to become plug-flow, while the 4th test was characterized as dispersive flow, tending to a high degree of mixing. In all tests, apparent deviations, probably caused by stagnant areas or dead zones, short-circuits and internal recirculation phenomena, were observed, confirming that the useful volume of GT was not fully utilized. Although not part of the scope of this work, the efficiency in removing oils and greases was higher when the gravitational flotation was applied, whose mixture tends to the plug-flow type, which assists the degree of acquiescence and allows a greater accumulation of floated fat. As for the forced flotation through the aerators, much of the fat is oxidized and thus minimized, forming a light color slag (white) and of very low thickness at the top of the CG. However, because of its high degree of mixture, the retention efficiency, as expected, was shown to be lower than the gravitational process.

A pilot study on the noninvasive fluid hemodynamic investigation of coronary plaque / 中华心血管病杂志

Objective@#To characterize the hemodynamic force towards coronary plaque based on noninvasive coronary computed tomographic angiography and to investigate its relationship with plaque features and stenosis severity by computational fluid dynamics.@*Methods@#Twenty-six patients underwent invasive fractional flow reserve measurement following coronary computed tomography angiography examination from March to September 2016 were retrospectively included. Computational fluid dynamics was applied and wall shear stress (WSS) and axial plaque stress (APS), which extracted the axial component of hemodynamic stress acting on stenotic lesions, were calculated based on the results of noninvasive coronary computed tomographic angiography. Plaque analysis was performed to elucidate plaque features and relative plaque burden. The fluid dynamics distributions in lesions with different stenosis severity were investigated.@*Results@#Thirty-one coronary plaques with satisfactory imaging quality were analyzed, there were 11 (35.5%) dominant low WSS (<1 Pa) lesion and 20 high WSS lesion (64.5%), 8(25.8%) net retrograde APS lesion and 23(74.2%) anterograde lesion. Plaque volume was (78.5±48.6) mm3 and plaque burden was (69.1±12.1)% in the low WSS group, which was(60.5±57.3) mm3, and(57.5±14.0)%, respectively in the high WSS group, the plaque burden was significantly higher in the low WSS group than in the high WSS group (P=0.028), while the percentage of calcified plaque, fibrotic plaque and lipid core volume were similar between the two groups (P>0.05). Plaque volume was (79.7±69.1) mm3 and plaque burden was(68.7±13.7)% in the group with anterograde-dominant APS plaque, which was(61.7±24.9)mm3, and(68.9±10.4)%, respectively in the net retrograde APS lesion group (P>0.05). Percentage of lipid core area was significantly higher in the anterograde lesion group than in the retrograde lesion group ((25.1±18.1)% vs.(10.8±12.7)%, P=0.049). Both WSS and APS were significant higher in the severe obstructive coronary stenosis group than in non-severe obstructive coronary stenosis group (P<0.05). Although there was no difference in WSS between functional coronary ischemia group and non-functional coronary ischemia group ( (13.3±8.7) Pa vs. (12.5±14.2) Pa, P>0.05), the distribution of APS was different between the functional coronary ischemia group and non-functional coronary ischemia group ((1 698.8±652.6) Pa vs. (981.4±787.5) Pa, P<0.05).@*Conclusion@#WSS and APS can uniquely characterize the stenotic segment and has a strong relationship with lesion geometry. APS may be related to the necrotic core plaque and functional coronary ischemia. Clinical application of these hemodynamic and geometric indices may be helpful to assess the future risk of plaque progress and plaque rupture, which will be helpful on determining respective treatment strategy for patients with coronary artery disease.

Avaliação do comportamento hidrodinâmico de reator anaeróbio de manta de lodo e fluxo ascendente com diferentes configurações do sistema de distribuição do afluente utilizando fluidodinâmica computacional / Hydrodynamic performance evaluation of an upflow anaerobic sludge blanket reactor with different configurations of the influent distribution system using computational fluid dynamics

RESUMO Compreender o comportamento hidrodinâmico de reatores biológicos pode auxiliar na detecção de problemas associados a falhas operacionais e de projeto, situações que prejudicam a eficiência do tratamento. Neste artigo, realizaram-se simulações da fluidodinâmica computacional (CFD) de escoamento de duas fases sólida-líquida de um reator anaeróbio de manta de lodo e fluxo ascendente (UASB), em escala piloto (160 L), com tempo de detenção hidráulica (TDH) de 10 h e vazão de 16 L.h-1. Um modelo Euler-Euler simplificado foi formulado para simular o comportamento hidrodinâmico da zona de reação, influenciada pela configuração do sistema de distribuição do afluente. Foram avaliadas quatro configurações do sistema de distribuição do afluente no reator: uma entrada na parte central (1) e duas entradas centrais (2), de fluxo ascendente; duas entradas nas laterais (3), de fluxo radial; e três entradas de fluxo descendente (4), utilizando geometrias bidimensionais e tridimensionais para verificar a formação de zonas mortas, curtos-circuitos hidráulicos e caminhos preferenciais. As melhores características hidrodinâmicas e a melhor distribuição do afluente foram verificadas na configuração 4, com melhor perfil de mistura do lodo com a fase líquida, na comparação com as demais configurações. Foi notada formação de vórtices na parte inferior do reator com maior concentração do lodo anaeróbio nessa configuração e de caminhos preferenciais nas laterais do reator na configuração 3, indicando mistura ineficiente do afluente com o lodo anaeróbio. O modelo demonstrou que a configuração do sistema de distribuição do afluente influencia significativamente o comportamento hidrodinâmico do reator UASB.

ABSTRACT Understanding the hydrodynamics behavior of biological reactors can help in the detection of problems related to operational failures and design that adversely affect the efficiency of the treatment. In this paper, computational fluid dynamics (CFD) simulations of two-phase liquid-solid flow were carried out in an upflow anaerobic sludge blanket reactor in pilot scale (160 L), with hydraulic retention time (HRT) of 10 h and flowrate 16 L.h-1. The Euler-Euler approach was formulated to simulate the reaction zone hydrodynamics. Four configurations of the influent distribution system in the reactor were evaluated: one central inlet (1) and two central inlets (2), upflow; two lateral inlets (3), radial flow; and three inlets, downflow (4), using two and three-dimensional geometries to verify the formation of dead zones, hydraulic short-circuiting and preferential pathways. Better influent distribution and greater mixture profile of the sludge with the liquid phase were found in the configuration 4, compared to the others by the formation of vortices in the bottom part of the reactor with higher concentration of anaerobic sludge. Formation of preferential pathways was noted in the lateral inlets of the reactor in the configuration 3, indicating an inefficient mixture of the influent with the sludge. The model demonstrates that the configuration of the influent distribution system significantly influences the hydrodynamics behavior of the UASB reactor.

Numerical investigation of laser iridotomy influence on shear stress exerted on corneal endothelial cells / 医用生物力学

Objective To study the influence of laser peripheral iridotomy (LPI) on aqueous humor flow in eyes of patients and fluid shear stress exerted on the corneal endothelial cells. Methods A complete three-dimensional geometric eye model was established by CAD software with references to human eye geometric data from the literature. Numerical simulations on the flow conditions of aqueous humor and the shear stress exerted on corneal endothelial cells after LPI surgery were performed using finite element software. The simulation results of shear stresses at different positions of the laser hole in the iris before and after LPI surgery were compared. Results If the laser hole punched more closer to the pupil axis in iris, the shear stress exerted on corneal inner surface would be smaller. The maximum shear stress exerted on corneal endothelium was 16.5, 25.8, 57.0, 179.8 mPa when the distance between laser hole and the pupil axis was 4.0, 4.5, 5.0, 5.5 mm, respectively. With laser hole at 3 and 6 o’clock orientation, the maximum shear stress exerted on corneal inner surface was 13.7% and 4.2% greater than that at 12 o’clock position (56.95 mPa). ConclusionsLPI can influence the intraocular aqueous humor flow and shear stress exerted on corneal endothelial cells. The suitable position can decrease the shear stress exerted on corneal endothelial cells and reduce the risk of postoperative bullous keratopathy for patients after LPI surgery.

Analysis of vertebrobasilar dolichoectasia based on computational fluid dynamics / 北京大学学报(医学版)

Objective:To anslysis the hemodynamic states of vertebrobasilar dolichoectasia based on computational fluid dynamics technique.Methods:The original DICOM format image data from a patient with vertebrobasilar dolichoectasia (VBD), were imported by the Mimics software directly,and the 3D Objects were constructed.The simulation of model was made with Ansys software, the hemodynamic pa-rameters such as streamlines, wall shear stress( WSS) and wall pressure were described.Results:There was stable laminar flow in proximal basilar artery and was no blood flow mixed by bilateral vertebral arter-y.However, Spiral flows were appeared in distal tortuous basilar artery.The low WSS regions in the ver-tebra-basilar junction section and inferior segment of basilar artery were coincide with the high wall pres-sure regions.It could be speculated the initial growth regions might be located in the vertebra-basilar junction section and inferior segment of basilar artery.Local regions with low WSS and high wall pressure might be associated with the occurrence and development of VBD.Conclusion: CFD numerical simula-tion maybe can provide a theoretical basis for the role of hemodynamic factors in occurrence and develop-ment of VBD.

Characteristics of nasal sinus lfow in patients with chronic sinusitis before and after endoscopic sinus surgery / 中国耳鼻咽喉头颈外科

[ABSTRACT]OBJECTIVETo evaluate the curative effect of endoscopic sinus surgery from the viewpoint of biomechanics analysis.METHODSWe select one case undergoing nasal endoscopic surgery for chronic sinusitis patients, after half year follow-up and collect preoperative and postoperative spiral CT data to build a numerical model of nasal cavity and paranasal sinuses with computer numerical simulation (CFD) research methods, to explore nasal airflow distribution and flow field characteristics of value changes before and after the operation. Patients undergo subjective assessments: nasal obstruction of VAS score, olfactory VAS score, SNOT-20, objective assessment: Lund Kennedy score, Lund Mackay score, saccharin test time and acquisition clinical efficacy data to verify the credibility of the analysis method is feasible and the results. RESULTSThe nasal resistance after endoscopic sinus surgery in nasal cavity and paranasal sinuses numerical simulation decreased, middle meatus of nose and nasal air flow velocity decreased, the pressure change slightly;nasal threshold region, middle turbinate head end section in maxillary sinus ostium section, after nearly sieve horizontal cross-section average velocity decreased, nasal airflow for the mucosa of the shear stress reduced. The volume of the nasal cavity and the area of the mucosa was increased, the volume ratio was decreased, the subjective and subjective assessment of the patients was improved, and the objective assessment was lighten.CONCLUSIONAerodynamic rules are presented through the calculation of numerical simulation of fluid mechanics which is invisible before. Better understanding of changes in the nasal airflow distribution and the changes of flow field characteristics can be useful to establish nasal endoscopic surgery in numerical analysis of offshore platform,which provides a new research tool for the understanding of the pathophysiology of chronic sinusitis by endoscopic sinus surgery.

Influence of fish farming in net cages on phytoplankton structure: a case study in a subtropical Brazilian reservoir / Influência do cultivo de peixes em tanques-rede sobre a estrutura do fitoplâncton: estudo de caso em um reservatório subtropical brasileiro

This study investigated the enrichment influence due to fish farming in net cages on the phytoplankton composition, density and diversity in two arms of a subtropical reservoir (Salto Caxias, Paraná). There were no statistically significant differences in the phytoplankton composition and diversity, as well as for concentrations of nutrients among the handled treatment. The density values were higher during the summer. Richness and Shannon diversity values were low during the study period. The equitability values were high during the winter and low in the summer. Variations of phytoplankton community and nutrients were mainly influenced by seasonality. The absence of significant differences between the treatments was probably due to the small number of net cages and fish used, as well as to the hydrodynamics of the studied environments, which are influenced by upstream rivers inflows.

Este estudo investigou os efeitos do enriquecimento devido ao cultivo de peixes em tanques-rede sobre a composição, densidade e diversidade fitoplanctônica em dois braços de um reservatório subtropical (Salto Caxias, Paraná). Não foram registradas diferenças significativas para a composição e diversidade fitoplanctônica e para as concentrações de nutrientes entre os tratamentos utilizados. A densidade foi maior durante o verão. Os valores de riqueza de espécies e diversidade de Shannon foram baixos durante todo o período de estudo. A equitabilidade foi elevada no inverno e baixa no verão. As variações da comunidade fitoplanctônica e dos nutrientes parecem ter sido influenciadas principalmente pela sazonalidade. A ausência de diferenças significativas entre os tratamentos, provavelmente se devem ao pequeno número de tanques e peixes utilizados, e à hidrodinâmica dos ambientes estudados, os quais são influenciados pelos influxos dos rios à montante.

Considerations of Blood Properties, Outlet Boundary Conditions and Energy Loss Approaches in Computational Fluid Dynamics Modeling / 신경중재치료의학

Despite recent development of computational fluid dynamics (CFD) research, analysis of computational fluid dynamics of cerebral vessels has several limitations. Although blood is a non-Newtonian fluid, velocity and pressure fields were computed under the assumptions of incompressible, laminar, steady-state flows and Newtonian fluid dynamics. The pulsatile nature of blood flow is not properly applied in inlet and outlet boundaries. Therefore, we present these technical limitations and discuss the possible solution by comparing the theoretical and computational studies.

Changes of biliary hydrodynamics on the formation of intrahepatic bile duct stones / 中华消化外科杂志

Intrahepatic bile duct stones located at the upper part of the hepatic duct.The percentage of intrahepatic biliary cholesterol calculus is increasing in recent years,and the incidence of this type of bile duct stones is free from infection or obstruction.The formation of intrahepatic bile duct stones might not only related to the micro-environment changes in the biliary tract,but also related to the changes of metabolic function of hepatocytes or cholangiocytes.In this article,the mechanism of biliary hydrodynamics on the formation of intrahepatic bile duct stones was reviewed.

Considerações hidrodinâmicas sobre a derivação liquórica V: alterações nos dimensionamentos originais do sistema valvular no momento do implante alteram suas características hidrodinâmicas e induzem a erros de avaliação clínica pelo neurocirurgião / Modifications in catheter dimensions upon shunt implantation - Revision affect shunt hydrodynamic profile and clinical judgment

Objetivo: Averiguar se as características hidrodinâmicas das válvulas se alteram significativamente quando os dimensionamentos originais são violados e a possível repercussão clínica desse fato. Métodos: Foi utilizada uma bancada de testes automatizada, conforme a norma ISO 7197. Um sistema valvular foi testado inicialmente com os componentes reconizados e embalados originalmente com o produto. A seguir, substituiu-se o cateter peritoneal original por diversos dimensionamentos encontrados no mercado nacional. Nos testes para a avaliação da influência do diâmetro do cateter no escoamento, foi utilizado sempre o mesmo comprimento original do cateter. Aplicou-se o mesmo raciocínio lógico para a análise do comprimento do cateter. Nove perfis hidrodinâmicos foram obtidos para as diferentes montagens valvulares. Resultados: Diminuições imperceptíveis no diâmetro do cateter peritoneal alteraram o perfil hidrodinâmico do sistema valvular testado. Alterações de 0,1 mm no diâmetro de um cateter peritoneal aumentaram o efeito resistivo do sistema valvular suficientemente para que ele funcionasse fora do perfil hidrodinâmico preconizado; o efeito resistivo se acentuou conforme o diâmetro diminuiu, e vice-versa. A diminuição do comprimento do cateter também influenciou significativamente no desempenho hidráulico da válvula, de um regime inicial de alta pressão para um regime de média pressão. Conclusão: Alterações de dimensionamento em cateteres peritoneais trazem complicações para o paciente e desorientam o julgamento clínico do neurocirurgião no período pós-implante, pois o sistema valvular funcionará em regime hidráulico fora do especificado, e o raciocínio lógico do neurocirurgião também se torna comprometido. Esse fato pode ser crítico principalmente em crianças e neonatos. Não foram identificados relatos desse fato na literatura que antecede esta apresentação.

Objective: Check if the hydrodynamic characteristics of the valves change significantly when the original sizing are violated, and the possible clinical consequences of this fact. Methods: One shunt system was randomly submitted to hydraulic forces in a bench test according to ISO 7197, for 50, 40, 30, 20, 10 and 5 ml/h flow, in six sequential tests, and each sequential test was repeated 7 times. Results are the mean flow for the 7 events. Maintaining original peritoneal length of 1,200 mm, data were collected for i.d. catheter diameters of 1,5, 1,2, 1,1, and 1,0 mm. Maintaining original i.d., peritoneal catheter length was sequentially cut and tested every 10 cm down to 600 mm. Results: Changes in the order of 0,1 mm in catheter inner diameter changes the hydrodynamic profile of the shunt system. Cutting a peritoneal catheter by also changes its original hydrodynamic profile. Shunt will perform in a lower pressure setting from originally specified. Conclusion: Cutting peritoneal catheters upon implantation or revisions is a fact, especially in pediatric patients. Depending on the cutting length of the peritoneal catheter, the shunt system implanted will not perform according the its specifications, being a lower resistance shunt than preconized by the manufacturer, and the neurosurgeon may have misjudgments whenever the patient requires care for shunt malfunction.