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Communications in Computational Physics 2014年第1期15卷 126-152页

作者： Hoang-Ngan Nguyen ricardo cortez Center for Computational Science Tulane University6823 St.Charles AveNew OrleansLouisiana70118USA.

We focus on the problem of evaluating the velocity field outside a solid object moving in an incompressible Stokes flow using the boundary integral *** points near the boundary,the integral is nearly singular,and accurate computation of the velocity is not *** way to overcome this problem is to regularize the integral *** method of regularized Stokeslet(MRS)is a systematic way to regularize the kernel in this *** a specific blob function which is widely used,the error of the MRS is only of first order with respect to the blob *** prove that this is the case for radial blob functions with decay propertyφ(r)=O(r−3−α)when r→∞for some constantα>*** then find a class of blob functions for which the leading local error term can be removed to get second and third order errors with respect to blob *** the addition of these terms might give a flow field that is not divergence free,we introduce a modification of these terms to make the divergence of the corrected flow field close to zero while keeping the desired ***,these dominant terms are explicitly expressed in terms of blob function and so the computation time is negligible.

关键词： Stokes flow regularized Stokeslet boundary integral equation nearly singular integral.

An Explicit Formula for Two-Dimensional Singly-Periodic Regularized Stokeslets Flow Bounded by a Plane Wall

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Communications in Computational Physics 2018年第1期23卷 142-167页

作者： Forest O.Mannan ricardo cortez Department of Mathematics Tulane UniversityNew OrleansLouisiana 70118-5665USA

We derive a closed form expression for the regularized Stokeslet in two space dimensions with periodic boundary conditions in the x-direction and a solid plane wall at y=*** accommodate the no-slip condition on the wall,a system of images for the regularized Stokeslets was *** periodicity is enforced by writing all elements of the image system in terms of a Green’s function whose periodic extension is *** the formulation is derived in the context of regularized Stokeslets,the expression for the traditional(singular)Stokeslet is easily found by taking the limit as the regularization parameter approaches *** new formulation is validated by comparing results of two test problems:the Taylor infinite waving sheet and the motion of a cylinder moving near a *** an example of an application,we use our formulation to compute the motion and flow generated by cilia using a model that does not prescribe the motion so that the beat period and synchronization of neighboring cilia are a result of the forces developed along the cilia.

关键词： Regularized Stokeslets singly-periodic flow method of images

Lagrangian Mesh Model with Regridding for Planar Poiseuille Flow

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Communications in Computational Physics 2017年第6期22卷 112-132页

作者： Jingxuan Zhuo ricardo cortez Robert Dillon Department of Mathematics and Statistics Washington State UniversityUSA Department of Mathematics Tulane UniversityUSA

Many biological settings involve complex fluids that have non-Newtonian mechanical responses that arise from suspended *** contrast,Newtonian fluids are liquids or mixtures of a simple molecular structure that exhibit a linear relationship between the shear stress and the rate of *** modeling complex fluids,the extra stress from the non-Newtonian contribution must be included in the governing *** this study we compare Lagrangian mesh and Oldroyd-B formulations of fluidstructure interaction in an immersed boundary *** start-up phase of planar Poiseuille flow between two parallel plates is used as a test case for the fluid *** Newtonian and Oldroyd-B fluids there exist analytical solutions which are used in the comparison of simulation and theoretical *** Lagrangian mesh results are compared with Oldroyd-B using comparable parameters.A regridding algorithm is introduced for the Lagrangian mesh *** show that the Lagrangian mesh model simulations with regridding produce results in close agreement with the Oldfoyd-B model.

关键词： Lagrangian mesh model Oldroyd-B immersed boundary method viscoelastic fluid regridding methods

Use of the American Society of Anesthesiologists Classification as an Additional Planning Tool for Renal Cell Carcinoma Assessment

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Journal of Cancer Therapy 2013年第9期4卷 7-14页

作者： Daniel Beltrame Ferreira Stenio de Cassio Zequi Walter Henriques da Costa Diego Abreu Clavijo ricardo Decia Deusdedit cortez Neto Renato Rosa de Oliveira Gustavo Cardoso Guimaraes Ademar Lopes Urology Division Department of Pelvic SurgeryA.C.Camargo Cancer CenterSao PauloBrazil Department of Urology Pasteur HospitalMontevideoUruguay

Objective: To determine the prognostic value of the American Society of Anesthesiologists (ASA) classification and of the main clinical pathologic variables in renal cell carcinoma (RCC) patients who underwent surgical treatment. Methods: In this international collaborative study, 376 RCC patients who underwent partial nephrectomy (PN) or radical nephrectomy (RN) during the period 1989-2009 were assessed. The pathological data were reviewed by a single pathologist, and all of the surgically treated patients had been previously evaluated by a team of anesthesiologists and classified as ASA 1, ASA 2, or ASA 3. Results: In total, 318 patients were included in the study, with a mean followup of 48 months. Incidental tumors represented 47% of the cases, while 11.6% presented with metastases at diagnosis. Among the patients assessed, 38 (11.9%) were classified as ASA 1, 213 (67%) as ASA 2, and 67 (21.1%) as ASA 3. An association between the ASA classification and the main clinicopathological variables of RCC was observed. The univariate analysis for overall survival (OS) revealed significant differences in the survival curves according to the ASA classification (p < 0.001). High-grade neoplasms, the presence of metastasis at diagnosis, clinical stage III/IV, and incidental tumors remained as independent predictors of survival. Moreover, the multivariate analysis revealed a negative impact of the ASA classification on OS (p = 0.001). Conclusions: The present study demonstrated a correlation between the ASA classification and the main prognostic factors of RCC and its impact on survival rates. ASA 3 patients had more aggressive tumors, increased risk of perioperative complications, and worse outcomes compared with ASA1 or ASA 2. Thus, the ASA classification may be considered an additional tool for assessing and planning the treatment of RCC patients.

关键词： Comorbidity Renal Cell Carcinoma ASA Prognosis Oncology

Synthesis of Solid Acid Catalysts Based on TiO2- SO42-and Pt/TiO2- SO42-Applied in n-Hexane Isomerization

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Open Journal of Metal 2013年第3期3卷 34-44页

作者： Juan Manuel Hernández Enríquez Luz Aracely cortez Lajas ricardo García Alamilla Estefanía ángeles San Martín Pedro García Alamilla Edward Brent Handy Guadalupe Cárdenas Galindo Luz Arcelia García Serrano CIEP Facultad de Ciencias Químicas Universidad Autónoma de San Luis Potosí Av. Dr. Manuel Nava #6 Zona Universitaria 78210 San Luis Potosí San Luis Potosí México Instituto Politécnico Nacional Centro Interdisciplinario de Investigaciones y Estudios sobre Medio Ambiente y Desarrollo 30 de Junio #1520 Barrio La Laguna Ticomán 07340 México D.F. México Instituto Tecnológico de Cd. Madero División de Estudios de Posgrado e Investigación Juventino Rosas y Jesús Urueta S/N Col. Los Mangos 89440 Cd. Madero Tamaulipas México Universidad Juárez Autónoma de Tabasco División Académica de Ciencias Agropecuarias Avenida Universidad S/N Zona Cultura Colonia Magisterial 86040 Villahermosa Tabasco México

The physicochemical properties and catalytic activity of pure and sulfated titanium oxide (TiO2 and ) is described in this work. Titanium hydroxide synthesized by the sol-gel method was impregnated with a 1 N H2SO4 solution, varying amount of sulfate ions () in the range from 10 to 20 wt%. Pure and modified hydroxides were calcined at 500°C for 3 h and then characterized by TGA-DTG, XRD, BET, FT-IR, potentiometric titration with n-butylamine and 2-propanol dehydration. Catalytic activity of materials was tested in the n-hexane isomerization at 350°C. The results showed that TiO2 and mainly developed anatase phase. All have acceptable specific surface area (95-105 m2/g). Potentiometric titration with n-butylamine revealed that showed higher acidity (430-530 mV) than compared to pure TiO2 (﹣15 mV), indicating that this oxide only has weak acidity. The results showed good relationship between acidity determined by potentiometric titration with n-butylamine and the catalytic activity evaluated by 2-propanol dehydration and n-hexane isomerization. Titanium oxide with 20 wt% ofions was the material that demonstrated the highest catalytic activity for both reactions.

关键词： Acid Catalysts Sulfated Titanium Oxide Physico-Chemical Properties n-Hexane Isomerization

Physico-Chemical Features and Catalytic Activity of ZrO2-MoO3

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材料科学与工程（中英文版） 2010年第9期4卷 1-9页

作者： Hernandez Juan Garcia Luz cortez Luz Garcia ricardo Handy Brent Cairdenas Maria Cueto Arturo Instituto Politecnico Nacional Escuela Superior de Ingenieria Textil Av. lnstituto Politecnico Nacional S/N Edificio # 8 Col. Linda Vista Mexico D.F. 07738. Mexico Instituto Tecnologico de Cd. Madero Division de Estudios de Posgrado e Investigacion Cd. Madero Tam. 89440 Mexico CIEP Facultad de Ciencias Qulmicas Universidad Aut6noma de San Luis Potosi San Luis Potosl 78210 Mdxico Universidad Autonoma Metropolitana-Azcapotzalco Av. San Pablo #180 Col. Reynosa Tamaulipas Delegacin Azcapotzalco Mexico D.F. 02200 oMexico

Zirconium hydroxide synthesized by sol-gel was impregnated with an aqueous solution of ammonium heptamolybdate in order to obtain 15 wt% of MoO3 on ZrO2. Pure and modified hydroxides were calcined at 400, 500, and 600 oC. In order to evaluate the catalytic activity for n-hexane isomerization, the materials were impregnated with 0.5 wt% of platinum and treated at 400 oC. For pure ZrO2 it was observed that the surface area decreases from 144 to 18 m2/g when the calcination temperature increases from 400 to 600 oC. The addition of Mo to zirconia increases the specific surface area (238-130 m2/g) in samples treated at the same temperatures. Pure zirconia transformed from tetragonal to monoclinic phase when calcined between 400 and 600 °C. However, this transformation did not occur in the ZrO2-MoO3 supports. The n-butylamine results showed that all the ZrO2-MoO3 supports presented a higher acidity (> 255 mV) than that corresponding to pure ZrO2 (- 48 mV), which presented only weakly acidic sites. Pt/ZrO2-MoO3 calcined at 600 oC proved to be the best catalyst for n-hexane isomerization, presenting a high selectivity to isomerization products (82%) at high conversion (72%).

关键词： MoO3 ZrO2 催化活性物理化学特征氢氧化锆焙烧温度比表面积浸渍材料