Extraction and isolation of dictamnine, obacunone and fraxinellone from Dictamnus dasycarpus Turcz. by supercritical fluid extraction and high-speed counter-current chromatography

Supercritical fluid extraction was used to extract active compounds from the Chinese traditional medicinal D. dasycarpus under the pressure of 30 MPa and temperature of 45 ºC. Further separation and purification was established by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.8:1.3:0.9, volume ratio). The separation yielded a total of 47 mg of dictamnine, 24 mg of obacunone and 83 mg of fraxinellone from 1.0 g of the crude extract in one step separation with the purity of 99.2, 98.4 and 99.0%, respectively, as determined by HPLC. The chemical structures of these compounds were identified by ESI-MS, IR, ¹H-NMR and 13C-NMR.

Intraspecific variability of Holostylis reniformis: concentration of lignans, as determined by maceration and supercritical fluid extraction (SFE-CO2), as a function of plant provenance and plant parts

Maceration and supercritical fluid extraction were used to prepare extracts from parts of plants (Holostylis reniformis) collected in two different regions of Brazil. ¹H NMR, HPLC-DAD-ESI/MS, HPLC-DAD, GC-MS, and chemometric techniques were used to analyse lignans in the extracts and showed that yields of SFE-CO2 were less than or equal to those of hexane maceration extracts. These analyses, in conjunction with the concentrations of aliphatic hydrocarbons, fatty acids and their methyl and ethyl derivatives in the extracts, also allowed the chemical composition of parts and provenance of the plant to be differentiated.

Super/subcritical fluid chromatography with packed columns: state of the art and applications

Separations using supercritical fluid chromatography (SFC) with packed columns have been re-discovered and explored in recent years. SFC enables fast and efficient separations and, in some cases, gives better results than high performance liquid chromatography (HPLC). This paper provides an overview of recent advances in SFC separations using packed columns for both achiral and chiral separations. The most important types of stationary phases used in SFC are discussed as well as the most critical parameters involved in the separations and some recent applications.

Simulating Fluid Flow in a Compressed Valve

The objective of the work is to study fluid flow behavior through a pinch valve and to estimate the flow coefficient (KV ) at different opening positions of the valve. The flow inside a compressed valve is more complex than in a straight pipe, and it is one of main topics of interest for engineers in process industry. In the present work, we have numerically simulated compressed valve flow at different opening positions. In order to simulate the flow through pinch valve, several models of the elastomeric valve tube (pinch valve tube) at different opening positions were constructed in 2D-axisymmetric and 3D geometries. The numerical simulations were performed with the CFD packages; ANSYS FLUENT and ANSYS CFX by using parallel computing. The distributions of static pressure, velocity and turbulent kinetic energy have been studied at different opening positions of the valve in both 2D-axisymmetric and 3D experiments. The flow coefficient (KV ) values have been measured at different valve openings and are compared between 2D-axisymmetric and 3D simulation results.

Methods and Models for Accelerating Dynamic Simulation of Fluid Power Circuits

The objective of this dissertation is to improve the dynamic simulation of fluid power circuits. A fluid power circuit is a typical way to implement power transmission in mobile working machines, e.g. cranes, excavators etc. Dynamic simulation is an essential tool in developing controllability and energy-efficient solutions for mobile machines. Efficient dynamic simulation is the basic requirement for the real-time simulation. In the real-time simulation of fluid power circuits there exist numerical problems due to the software and methods used for modelling and integration. A simulation model of a fluid power circuit is typically created using differential and algebraic equations. Efficient numerical methods are required since differential equations must be solved in real time. Unfortunately, simulation software packages offer only a limited selection of numerical solvers. Numerical problems cause noise to the results, which in many cases leads the simulation run to fail. Mathematically the fluid power circuit models are stiff systems of ordinary differential equations. Numerical solution of the stiff systems can be improved by two alternative approaches. The first is to develop numerical solvers suitable for solving stiff systems. The second is to decrease the model stiffness itself by introducing models and algorithms that either decrease the highest eigenvalues or neglect them by introducing steady-state solutions of the stiff parts of the models. The thesis proposes novel methods using the latter approach. The study aims to develop practical methods usable in dynamic simulation of fluid power circuits using explicit fixed-step integration algorithms. In this thesis, twomechanisms whichmake the systemstiff are studied. These are the pressure drop approaching zero in the turbulent orifice model and the volume approaching zero in the equation of pressure build-up. These are the critical areas to which alternative methods for modelling and numerical simulation are proposed. Generally, in hydraulic power transmission systems the orifice flow is clearly in the turbulent area. The flow becomes laminar as the pressure drop over the orifice approaches zero only in rare situations. These are e.g. when a valve is closed, or an actuator is driven against an end stopper, or external force makes actuator to switch its direction during operation. This means that in terms of accuracy, the description of laminar flow is not necessary. But, unfortunately, when a purely turbulent description of the orifice is used, numerical problems occur when the pressure drop comes close to zero since the first derivative of flow with respect to the pressure drop approaches infinity when the pressure drop approaches zero. Furthermore, the second derivative becomes discontinuous, which causes numerical noise and an infinitely small integration step when a variable step integrator is used. A numerically efficient model for the orifice flow is proposed using a cubic spline function to describe the flow in the laminar and transition areas. Parameters for the cubic spline function are selected such that its first derivative is equal to the first derivative of the pure turbulent orifice flow model in the boundary condition. In the dynamic simulation of fluid power circuits, a tradeoff exists between accuracy and calculation speed. This investigation is made for the two-regime flow orifice model. Especially inside of many types of valves, as well as between them, there exist very small volumes. The integration of pressures in small fluid volumes causes numerical problems in fluid power circuit simulation. Particularly in realtime simulation, these numerical problems are a great weakness. The system stiffness approaches infinity as the fluid volume approaches zero. If fixed step explicit algorithms for solving ordinary differential equations (ODE) are used, the system stability would easily be lost when integrating pressures in small volumes. To solve the problem caused by small fluid volumes, a pseudo-dynamic solver is proposed. Instead of integration of the pressure in a small volume, the pressure is solved as a steady-state pressure created in a separate cascade loop by numerical integration. The hydraulic capacitance V/Be of the parts of the circuit whose pressures are solved by the pseudo-dynamic method should be orders of magnitude smaller than that of those partswhose pressures are integrated. The key advantage of this novel method is that the numerical problems caused by the small volumes are completely avoided. Also, the method is freely applicable regardless of the integration routine applied. The superiority of both above-mentioned methods is that they are suited for use together with the semi-empirical modelling method which necessarily does not require any geometrical data of the valves and actuators to be modelled. In this modelling method, most of the needed component information can be taken from the manufacturer’s nominal graphs. This thesis introduces the methods and shows several numerical examples to demonstrate how the proposed methods improve the dynamic simulation of various hydraulic circuits.

From Fluid Dynamics to Human Psychology.What Drives Financial Markets Towards Extreme Events

For decades researchers have been trying to build models that would help understand price performance in financial markets and, therefore, to be able to forecast future prices. However, any econometric approaches have notoriously failed in predicting extreme events in markets. At the end of 20th century, market specialists started to admit that the reasons for economy meltdowns may originate as much in rational actions of traders as in human psychology. The latter forces have been described as trading biases, also known as animal spirits. This study aims at expressing in mathematical form some of the basic trading biases as well as the idea of market momentum and, therefore, reconstructing the dynamics of prices in financial markets. It is proposed through a novel family of models originating in population and fluid dynamics, applied to an electricity spot price time series. The main goal of this work is to investigate via numerical solutions how well theequations succeed in reproducing the real market time series properties, especially those that seemingly contradict standard assumptions of neoclassical economic theory, in particular the Efficient Market Hypothesis. The results show that the proposed model is able to generate price realizations that closely reproduce the behaviour and statistics of the original electricity spot price. That is achieved in all price levels, from small and medium-range variations to price spikes. The latter were generated from price dynamics and market momentum, without superimposing jump processes in the model. In the light of the presented results, it seems that the latest assumptions about human psychology and market momentum ruling market dynamics may be true. Therefore, other commodity markets should be analyzed with this model as well.

Application of Computational Fluid Dynamics in Modeling Blood Flow in Human Thoracic Aorta

The aim of this study was to simulate blood flow in thoracic human aorta and understand the role of flow dynamics in the initialization and localization of atherosclerotic plaque in human thoracic aorta. The blood flow dynamics in idealized and realistic models of human thoracic aorta were numerically simulated in three idealized and two realistic thoracic aorta models. The idealized models of thoracic aorta were reconstructed with measurements available from literature, and the realistic models of thoracic aorta were constructed by image processing Computed Tomographic (CT) images. The CT images were made available by South Karelia Central Hospital in Lappeenranta. The reconstruction of thoracic aorta consisted of operations, such as contrast adjustment, image segmentations, and 3D surface rendering. Additional design operations were performed to make the aorta model compatible for the numerical method based computer code. The image processing and design operations were performed with specialized medical image processing software. Pulsatile pressure and velocity boundary conditions were deployed as inlet boundary conditions. The blood flow was assumed homogeneous and incompressible. The blood was assumed to be a Newtonian fluid. The simulations with idealized models of thoracic aorta were carried out with Finite Element Method based computer code, while the simulations with realistic models of thoracic aorta were carried out with Finite Volume Method based computer code. Simulations were carried out for four cardiac cycles. The distribution of flow, pressure and Wall Shear Stress (WSS) observed during the fourth cardiac cycle were extensively analyzed. The aim of carrying out the simulations with idealized model was to get an estimate of flow dynamics in a realistic aorta model. The motive behind the choice of three aorta models with distinct features was to understand the dependence of flow dynamics on aorta anatomy. Highly disturbed and nonuniform distribution of velocity and WSS was observed in aortic arch, near brachiocephalic, left common artery, and left subclavian artery. On the other hand, the WSS profiles at the roots of branches show significant differences with geometry variation of aorta and branches. The comparison of instantaneous WSS profiles revealed that the model with straight branching arteries had relatively lower WSS compared to that in the aorta model with curved branches. In addition to this, significant differences were observed in the spatial and temporal profiles of WSS, flow, and pressure. The study with idealized model was extended to study blood flow in thoracic aorta under the effects of hypertension and hypotension. One of the idealized aorta models was modified along with the boundary conditions to mimic the thoracic aorta under the effects of hypertension and hypotension. The results of simulations with realistic models extracted from CT scans demonstrated more realistic flow dynamics than that in the idealized models. During systole, the velocity in ascending aorta was skewed towards the outer wall of aortic arch. The flow develops secondary flow patterns as it moves downstream towards aortic arch. Unlike idealized models, the distribution of flow was nonplanar and heavily guided by the artery anatomy. Flow cavitation was observed in the aorta model which was imaged giving longer branches. This could not be properly observed in the model with imaging containing a shorter length for aortic branches. The flow circulation was also observed in the inner wall of the aortic arch. However, during the diastole, the flow profiles were almost flat and regular due the acceleration of flow at the inlet. The flow profiles were weakly turbulent during the flow reversal. The complex flow patterns caused a non-uniform distribution of WSS. High WSS was distributed at the junction of branches and aortic arch. Low WSS was distributed at the proximal part of the junction, while intermedium WSS was distributed in the distal part of the junction. The pulsatile nature of the inflow caused oscillating WSS at the branch entry region and inner curvature of aortic arch. Based on the WSS distribution in the realistic model, one of the aorta models was altered to induce artificial atherosclerotic plaque at the branch entry region and inner curvature of aortic arch. Atherosclerotic plaque causing 50% blockage of lumen was introduced in brachiocephalic artery, common carotid artery, left subclavian artery, and aortic arch. The aim of this part of the study was first to study the effect of stenosis on flow and WSS distribution, understand the effect of shape of atherosclerotic plaque on flow and WSS distribution, and finally to investigate the effect of lumen blockage severity on flow and WSS distributions. The results revealed that the distribution of WSS is significantly affected by plaque with mere 50% stenosis. The asymmetric shape of stenosis causes higher WSS in branching arteries than in the cases with symmetric plaque. The flow dynamics within thoracic aorta models has been extensively studied and reported here. The effects of pressure and arterial anatomy on the flow dynamic were investigated. The distribution of complex flow and WSS is correlated with the localization of atherosclerosis. With the available results we can conclude that the thoracic aorta, with complex anatomy is the most vulnerable artery for the localization and development of atherosclerosis. The flow dynamics and arterial anatomy play a role in the localization of atherosclerosis. The patient specific image based models can be used to diagnose the locations in the aorta vulnerable to the development of arterial diseases such as atherosclerosis.

Estudo comparativo entre sling pubovaginal de parede vaginal e sling de fáscia do reto abdominal no tratamento da incontinência urinária de esforço

OBJETIVO: A cirurgia de sling pubovaginal é utilizada no tratamento da incontinência urinária de esforço (IUE) do tipo III e como resgate na falha de procedimentos anteriores. Tem índice de sucesso variando de 73 a 89%. Podem ser utilizados diversos materiais autólogos e sintéticos com semelhantes resultados. Nosso objetivo foi comparar o sling de parede vaginal com o de fáscia do reto abdominal quanto à eficácia e às complicações. MÉTODO: Foram estudadas 27 pacientes no período de 04/98 a 09/00, divididas em dois grupos: grupo I com nove pacientes submetidas a sling de parede vaginal; grupo II com 18 pacientes submetidas a sling de fáscia do reto abdominal. Todas foram submetidas a um estudo urodinâmico completo, classificadas quanto ao tipo de IUE, e seguidas no ambulatório de urologia. RESULTADOS: grupo I com média de idade de 51,4 anos, tempo de seguimento médio de 14,3 meses. Pressão de Perda aos Esforços (PPE) variando de 50 a 100cmH2O com média de 81,1cmH2O. Houve 66% de complicações. Taxa de sucesso de 88,8% e índice de satisfação 85 pontos. Grupo II com média de idade de 54,2 anos, seguimento médio de 19,3 meses. PPE variando de 45 a 92cmH2O, média de 65,5cmH2O. Houve 72% de complicações e sucesso de 88,8%. Índice de satisfação de 74 pontos. CONCLUSÕES: Os dados encontrados estão de acordo com a literatura, sendo os dois grupos comparáveis quanto à eficácia em período curto de seguimento. O grupo II apresentou maior número de complicações, assim como maior tempo de cateter vesical e menor índice de satisfação geral.

Tela de polipropileno versus correção sítio-especifica no tratamento do prolapso de parede vaginal anterior: resultados preliminares de ensaio clínico randômico

OBJETIVO: Comparar o uso de tela de polipropileno e correção sitio-específica no tratamento cirúrgico do prolapso vaginal anterior. MÉTODOS: Estudo prospectivo randômico comparativo em que foram operadas 32 pacientes com idades entre 50 e 75 anos, que apresentavam prolapso vaginal anterior estádio III ou IV, ou recidivado. A estática pélvica foi avaliada segundo as recomendações da International Continence Society (ICS), o sistema POP-Q e pelo Índice de Quantificação de Prolapso (POP-Q-I) Absoluto e Relativo. Para o rastreamento da incontinência urinária de esforço oculta todas as pacientes, sintomáticas ou não, foram submetidas a estudo urodinâmico em posição semi-ginecológica e semi-sentada, com redução do prolapso com pinça de Cheron. Registrou-se o tempo cirúrgico, o volume de sangramento intra-operatório e as complicações intra e pós-operatórias. O tempo de seguimento médio do estudo foi de 8,5 meses. RESULTADOS: Em relação aos resultados anatômicos ocorreu melhores resultados com a utilização de tela de polipropileno sobre o reparo sitio-específico. Em relação à morbidade cirúrgica, observou-se menor tempo cirúrgico no grupo em que utilizou-se tela. CONCLUSÃO: Houve superioridade dos resultados anatômicos obtidos com a utilização de tela de polipropileno sobre o reparo sitio-específico.

Prevenção do parto prematuro: emprego do toque vaginal e da ultra-sononografia transvaginal

Objetivo: avaliar o colo uterino por meio do toque vaginal e da ultra-sonografia transvaginal em gestantes de risco elevado para o parto prematuro. Métodos: durante o período compreendido entre fevereiro de 1995 e setembro de 1997 foram acompanhadas 38 gestantes com elevado risco para o parto prematuro entre a 20ª e 36ª semana de gestação. Estas pacientes foram submetidas semanalmente ao toque vaginal e ao exame ultra-sonográfico transvaginal. O toque vaginal avaliou o colo uterino quanto a dois parâmetros: comprimento e dilatação. A ultra-sonografia transvaginal estudou o comprimento e o diâmetro anteroposterior do colo uterino. Foram analisados os comportamentos destas medidas cervicais ao longo da gestação. Os dois métodos foram comparados quanto à avaliação cervical e à acurácia no diagnóstico do parto prematuro. Resultados: a incidência de partos prematuros foi de 18,4% (7/38). As medidas do comprimento cervical obtidas pela ultra-sonografia foram sempre maiores em relação às medidas obtidas pelo toque vaginal. Mediante análise pelo teste de hipóteses foram observadas uma relação indireta entre o comprimento cervical e a idade gestacional por meio do toque e do estudo ultra-sonográfico (p<0,05 e p<0,01, respectivamente) e uma relação direta entre a dilatação cervical e a idade gestacional observada pelo toque (p<0,01). Conclusões: dos parâmetros estudados por meio do toque e da ultra-sonografia transvaginal, o comprimento cervical ultra-sonográfico apresentou melhor acurácia no diagnóstico do parto prematuro, revelando ser o mais confiável para a avaliação das alterações cervicais em gestantes de risco elevado para o parto prematuro.

Histerectomia vaginal: o laparoscópico é necessário?

Objetivos: a laparoscopia pode auxiliar na conversão de uma histerectomia abdominal em vaginal quando esta última está contra-indicada, não devendo substituir a histerectomia vaginal simples quando esta é viável. Este estudo tem por objetivo discutir o papel da laparoscopia na histerectomia vaginal. Métodos: de fevereiro de 1995 a setembro de 1998, 400 pacientes foram consideradas candidatas à histerectomia vaginal. Foram excluídas as pacientes portadoras de prolapso uterino, tumor anexial associado e útero fixo ao toque bimanual. Os procedimentos foram realizados com a técnica de Heaney utilizando métodos de redução do volume uterino no caso de úteros miomatosos. Resultados: A média de idade e paridade foi de 46,9 anos e 3,2 partos, respectivamente. Vinte e nove pacientes (7,2%) eram nulíparas e 104 (26,0%) não tinham antecedente de parto vaginal. Trezentas e três pacientes (75,7%) apresentavam cirurgia pélvica prévia, sendo a cesárea a mais freqüente (48,7%). A principal indicação cirúrgica foi miomatose uterina (61,2%), e o volume uterino médio foi de 239,9 cm³ (30-1228 cm³). A histerectomia vaginal foi realizada com sucesso em 396 pacientes (99,0%), sendo que 73 cirurgias (18,2%) foram realizadas por residentes. O tempo cirúrgico médio foi de 45 min. A laparoscopia diagnóstica/cirúrgica foi realizada em 16 pacientes (4,0%). As complicações intra-operatórias incluíram 6 lesões vesicais (1,5%) e uma lesão retal (0,2%). Quatro procedimentos (1,0%) foram efetivados pela via abdominal. Ocorreram complicações pós-operatórias em 24 pacientes (6,0%). Duzentas e oitenta e uma pacientes (70,2%) receberam alta hospitalar 24 h após a cirurgia. Conclusões: O laparoscópio não parece ser necessário nos casos em que o útero é móvel e não existe tumor anexial associado. Em última análise, o principal papel do laparoscópio parece ser o de permitir que o ginecologista se dê conta de que histerectomia vaginal simples pode ser realizada na grande maioria dos casos.

Histerectomia Vaginal Assistida por Laparoscopia em Pacientes com Necessidade de Anexectomia

Objetivos: avaliar as vantagens da laparoscopia como instrumento para conversão de histerectomias abdominais em vaginais em pacientes com indicação de anexectomia concomitante, considerando-se a segurança e os custos hospitalares adicionais relativos ao procedimento. Pacientes e Métodos: estudo de caso controle envolvendo 9 pacientes submetidas à Histerectomia Vaginal Assistida por Laparoscopia (HVAL) e 18 pacientes-controle submetidas à Histerectomia Abdominal (HA), associadas à anexectomia. Foram avaliadas as características pré-operatórias e os resultados do procedimento. Os grupos HVAL e HA são semelhantes quanto à idade, paridade, cesáreas anteriores, cirurgias prévias e IMC. Resultados: o grupo HVAL apresentou tempo cirúrgico médio de 163,9 minutos e o grupo HA de 142,8 minutos. Não ocorreram complicações pós-operatórias no grupo HVAL, ao passo que no grupo HA houve 2 casos de deiscência de sutura e 1 caso de hérnia incisional. A mediana do tempo de internação foi de 1 dia no grupo HVAL e 2 dias no grupo HA; a mediana do período de convalescença por sua vez foi de 2 e 4 semanas respectivamente. No grupo HVAL, 55,6% das pacientes necessitaram de medicação analgésica no pós-operatório, o que ocorreu em 100% das pacientes do grupo HA. Conclusões: a HVAL mostrou-se vantajosa em relação à HA em termos de melhor recuperação e menor incidência de complicações no pós-operatório. O procedimento é factível com segurança em um Hospital Universitário, não implicando tampouco em custos adicionais com equipamentos ou instrumental.

Prevalência de cândida na flora vaginal de mulheres atendidas num serviço de planejamento familiar

RESUMO Objetivo: avaliar a prevalência de Candida sp. e a distribuição de suas espécies na flora vaginal de mulheres numa clínica de planejamento familiar. Método: estudo transversal no qual se avaliaram prospectivamente 72 mulheres não-grávidas, com ou sem queixas específicas, sendo coletadas amostras de secreção vaginal para cultura de leveduras, efetuada a medição do pH vaginal e anotados dados de achados do exame ginecológico. Resultados: leveduras pertencentes ao gênero Candida foram encontradas em 18 casos (25%). A C. albicans foi a espécie mais prevalente (77,8%) e conseqüentemente 22,2% foram não-albicans. Entre as não-albicans a espécie mais prevalente foi a C. glabrata (16,7%) seguida pela C. parapsilosis (5,6%). Prurido e ardor foram os únicos sintomas relacionados significativamente com a presença de cândida. Foi observado que a C. glabrata, ao contrário da C. albicans, não causa corrimento clinicamente verificável ao exame ginecológico. Não foram verificadas associações de alguns fatores predisponentes (idade, escolaridade e uso de contraceptivos) com a presença ou não de cândida. Conclusões: nossos resultados sugerem: a) uma alta prevalência de Candida sp. entre as mulheres (25%); b) que as espécies não-albicans desempenham um papel importante no meio vaginal; c) que prurido e ardor são os sintomas mais comuns na presença de cândida e d) que a C. glabrata não costuma causar corrimento vaginal ao exame ginecológico. Finalmente, é importante observar que nossos resultados são consistentes com o que a literatura internacional tem mostrado nos últimos anos.