Altered Doppler flow patterns in cirrhosis patients: an overview

Pooya Iranpour,Chandana Lall,Roozbeh Houshyar,Mohammad Helmy,Albert Yang,최준일,Garrett Ward,Scott C Goodwin 대한초음파의학회 2016 ULTRASONOGRAPHY Vol.35 No.1

Doppler ultrasonography of the hepatic vasculature is an integral part of evaluating precirrhotic and cirrhotic patients. While the reversal of the portal venous flow is a well-recognized phenomenon, other flow patterns, although not as easily understood, may play an important role in assessing the disease status. This article discusses the different characteristic flow patterns observed from the portal vein, hepatic artery, and hepatic vein in patients with liver cirrhosis or related complications and procedures. Knowledge of these different flow patterns provides additional information that may reinforce the diagnosis of cirrhosis, help in staging, and offer prognostic information for determining the direction of therapy. Doppler ultrasonography is invaluable when liver transplantation is being considered and aids in the diagnosis of cirrhosis and portal hypertension.

Simulation of continuous catalytic conversion of glycerol into lactic acid in a microreactor system: A CFD study

Pooya Jalal Sahandi,Mohammad Kazemeini,Samahe Sadjadi 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-

Hand in hand with the flourish of the biodiesel industry, glycerol (GLY) as an inconvenient by-product hasgenerated environmental and sustainability concerns. Devising measures for efficient transformation ofGLY into value-added products is a promising solution. In this contribution, the transformation of GLYto lactic acid (LA) as a valuable chemical was investigated in a continuous process for industrial applications. In this regard, a catalytic method using heterogeneous Cu nanoparticles in NaOH solution was studiedin a microreactor by a CFD simulation. A seven-inlet micromixer comprising an optimized mixing unitwas incorporated for uniform distribution of the species. The effects of various parameters upon the processperformance were considered and the optimum points were determined. Also, the extent of theinfluence of each variable on LA yield was evaluated using sensitivity analysis techniques. While higherLA yield could be obtained at extreme scenarios, optimum values of the Re and temperature for obtainingthe maximum performance under sensible operating conditions were determined to be 0.108 and 510.1 Kwhich led to the optimum yields of 67.8% and 59.5%, respectively. Moreover, the sensitivity analysisrevealed that the molar ratio of OH /GLY and temperature were the most and least significant parameters,respectively.

Optimization of supercritical extraction of galegine from Galega officinalis L.: Neural network modeling and experimental optimization via response surface methodology

Pooya Davoodi,Seyyed Mohammad Ghoreishi,Ali Hedayati 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.3

Supercritical CO2 extraction of galegine from Galega officinalis L. was carried out under different operating conditions of temperature (35-55 oC), pressure (10-30MPa), dynamic extraction time (30-150min), CO2 flow rate (0.5-2.5 mL/min) and constant static extraction time of 20 min. Design of experiment was by response surface methodology (RSM) using Minitab software 17. The response surface analysis accuracy was verified by the coefficient of determination (R2=93.4%) along with modified coefficient of determination (mod-R2=87.7%). The optimum operating conditions were found by using RSM modeling to be 42.8 oC, 22.7MPa, 141.5min and 2.15 mL/min, in which the maximum galegine extraction yield of 3.3932mg/g was obtained. Artificial neural network (ANN) using Levenberg- Marquardt backpropagation training function with six neurons in the hidden layer was implemented for the modeling of galegine extraction such that the coefficient of determination (R2) was 96.6%.

Encoding range minima and range top-2 queries

Davoodi, Pooya,Navarro, Gonzalo,Raman, Rajeev,Rao, S. Srinivasa The Royal Society 2014 Philosophical transactions. Series A, Mathematical Vol.372 No.2016

We consider the problem of encoding range minimum queries (RMQs): given an array A[1..n] of distinct totally ordered values, to pre-process A and create a data structure that can answer the query RMQ(i, j), which returns the index containing the smallest element in A[i..j], without access to the array A at query time. We give a data structure whose space usage is 2n + o(n) bits, which is asymptotically optimal for worst-case data, and answers RMQs in O(1) worst-case time. This matches the previous result of Fischer and Heun, but is obtained in a more natural way. Furthermore, our result can encode the RMQs of a random array A in 1.919n + o(n) bits in expectation, which is not known to hold for Fischer and Heun's result. We then generalize our result to the encoding range top-2 query (RT2Q) problem, which is like the encoding RMQ problem except that the query RT2Q(i, j) returns the indices of both the smallest and second smallest elements of A[i..j]. We introduce a data structure using 3.272n + o(n) bits that answers RT2Qs in constant time, and also give lower bounds on the effective entropy of the RT2Q problem.

Combined Antimicrobial Activity of Extracts from Quercus infectoria Galls and Scrophularia striata Aerial Parts for an Anticariogenic Herbal Mouthwash

Falakdin Pooya,Dastan Dara,Pourmoslemi Shabnam 대한약침학회 2023 Journal of pharmacopuncture Vol.26 No.1

Objectives: Dental caries is one of the most prevalent human diseases worldwide. The disease initiates with bacterial adherence to the tooth surface followed by the formation of dental plaques. Mutans streptococci and Candida albicans are principal oral microorganisms involved in the initiation and development of dental caries. Phytochemicals have been shown to possess promising antimicrobial properties against a wide range of microorganisms and can be used for the prevention and treatment of dental caries. Herein, we reviewed literature on plants that are traditionally used for their antimicrobial properties or possess promising anticariogenic activity. We selected aerial parts of Scrophularia striata (S. striata) and galls of Quercus infectoria (Q. infectoria) and investigated their antimicrobial activity against cariogenic microorganisms. Methods: Water soluble fractions were obtained from hydroalcoholic extracts of S. striata and Q. infectoria and their antimicrobial activity against Streptococcus mutans (S. mutans), Streptococcus sobrinus (S. sobrinus), and Candida albicans (C. albicans) was evaluated separately and in combination. The extracts were then used for preparing an herbal mouthwash whose stability and tannic acid content were evaluated over 60 days. Results: Q. infectoria gall extract possesses efficient antimicrobial activity that was synergistically enhanced in the presence of S. striata extract. Mouthwash prepared using these extracts showed desirable organoleptic characteristics, antimicrobial activity, and stability. Conclusion: Extracts of S. striata and Q. infectoria galls can be used together for preparing dental products with effective anticariogenic properties. Our study highlights the importance of extensive pharmacological investigations when using herbal products alone or in combination with other chemical substances.

Optimal Seismic Design of Reinforced Concrete Shear Wall-Frame Structures

Ali Kaveh,Pooya Zakian 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.7

Seismic design of Reinforced Concrete (RC) dual systems is performed as an optimization problem for which the charged system search algorithm is utilized as an optimizer. An efficient structural modeling is also presented for this purpose. Here, first databases are created based on ACI seismic criteria for beams, columns and shear walls. Formulations for optimal seismic design of dual systems (shear wall-frame) are proposed. With some modifications on these formulations, optimal seismic design of RC moment frames can also be performed. This procedure is along with ordinary design constraints and effective seismic design constraints. These constraints consist of beams, columns, shear wall design criteria, and some other seismic provisions. Cost of the structure is considered as the objective function. According to the results of the numerical example, the proposed methodology can be considered as a suitable practical approach for optimal seismic design of reinforced concrete shear wall-frame structures.

Propagation of elastic waves in thermally affected embedded carbon-nanotube-reinforced composite beams via various shear deformation plate theories

Farzad Ebrahimi,Pooya Rostami 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.4

The current study is dedicated to study the thermal effects of wave propagation in beams, reinforced by carbon nanotubes (CNT). Beams, made up of carbon nanotube reinforced composite (CNTRC) are the future materials in various high tech industries. Herein a Winkler elastic foundation is assumed in order to make the model more realistic. Mostly, CNTs are pervaded in cross section of beam, in various models. So, it is tried to use four of the most profitable reconstructions. The homogenization of elastic and thermal properties such as density, Yong’s module, Poisson’s ratio and shear module of CNTRC beam, had been done by the demotic rule of mixture to homogenize, which gives appropriate traits in such settlements. To make this investigation, a perfect one, various shear deformation theories had been utilized to show the applicability of this theories, in contrast to their theoretical face. The reigning equation had been derived by extended Hamilton principle and the culminant equation solved analytically by scattering relations for propagation of wave in solid bodies. Results had been verified by preceding studies. It is anticipated that current results can be applicable in future studies.

Buckling analysis of a sandwich plate with polymeric core integrated with piezo-electro-magnetic layers reinforced by graphene platelets

Mehdi, Mohammadimehr,Pooya, Nikbakhsh Techno-Press 2022 Advances in materials research Vol.11 No.4

In the present work, we proposed an analytical study on buckling behavior of a sandwich plate with polymeric core integrated with piezo-electro-magnetic layers such as BaTiO3 and CoFe2O4 reinforced by graphene platelets (GPLs). The Halpin-Tsai micromechanics model is used to describe the properties of the polymeric core. The governing equations of equilibrium are obtained from first-order shear deformation theory (FSDT) and the Navier's method is employed to solve the equations. The results show the effect of different parameters such as thickness, length, weight fraction of GPLs, and also effect of electric and magnetic field on critical buckling load. The result of this study can be obtained in the aerospace industry and also in the design of sensors and actuators.

Stress concentration factors in tubular T-joints stiffened with external ring under axial load

Hossein Nassiraei,Pooya Rezadoost Techno-Press 2023 Ocean systems engineering Vol.13 No.1

In this study, the SCFs in tubular T-joints stiffened with external ring under axial load are studied and discussed. After verification of the present numerical model with the results of several available experimental tests, 156 FE models were generated and analyzed to parametrically evaluate the effect of the joint geometry and the ring geometry on the SCFs. Results indicated that the SCF of the stiffened T-joints at crown point can be down to 24% of the SCF of the corresponding un-reinforced joint at the same point. Also, the effect of the ring on the SCF at saddle point is more remarkable than the effect of the ring on the SCF at crown point. Moreover, against un-reinforced joints under axial load, the SCF at saddle point of the stiffened joint is smaller than the SCF at crown point of that stiffened joint. The ring results in the redistribution of stresses in the ring and metal substrate. Also, the effect of the ring thickness on the decrease of the SCFs is slight and can be ignored. In final step, the geometric parameters affecting the SCFs of the stiffened T-joints are analyzed by multiple nonlinear regression analyses. An accurate formula is proposed for determining the SCFs.

A Bridgeless Buck-flyback PFC Converter with High PF and Dead Angles Eliminated

Zhengge Chen,Pooya Davari,Huai Wang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The inherent dead angles of the input line current in buck power factor correction (PFC) converter deteriorate the power factor (PF) and commonly extra switches with high control complexity are required to eliminate these dead angles. Alternatively, this paper proposed a topological solution using a simple single voltage loop control. The proposed switch integrated bridgeless buck-flyback PFC converter operates in buck-flyback mode and can automatically change to flyback mode when the dead angles occur. Bridgeless operation modes of the proposed converter are achieved by dual converter cells and the corresponding PF expression is derived. Besides, the inductors and transformers ratio is analyzed to ensure the high PF (>0.99) and the satisfactory input current harmonics (meet the IEC 61000-3-2 Class D limits) in the 100~240 Vac input voltage range. The 100 W prototypes of the conventional buck and the proposed converters are built for experimental tests, which confirm the effectiveness of the proposed topology.