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Stability analysis of slopes with planar failure using variational calculus and numerical methods

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Frontiers of Structural and Civil Engineering 2020年第5期14卷 1262-1273页

作者： Norly BELANDRIA RobertoÚCAR Francisco M.LEON Ferri HASSANI Geological Engineering School University of Los AndesMérida 5101Venezuela Mechanical Engineering School University of Los AndesMérida 5101Venezuela Department of Mining and Material Engineering McGill UniversityMontrealQC H3A 0E9Canada

This study investigates the technique of variational calculus applied to estimate the slope stability considering the mechanism of planar *** critical plane failure surface should be determined because it theoretically indicates the most unfavorable plane to be considered when stabilizing a slope to rectify the instability generated by several statistically possible *** generates integrals that can be solved by numerical methods,such as the Newton Cotes and the finite differences ***,a system of nonlinear equations is obtained and *** surface of the critical planar failure is determined by applying the condition of transversality in mobile boundaries,for which various examples are *** number of slices is varied in one of the examples,while the surface of the critical planar failure is determined in the *** are compared using analytical methods through axis *** the results obtained by considering normal stress,safety factors,and critical planar failure are nearly the same;however,in this research,a study is carried out for“n”number of slices using programming ***-routines are important because they can be applied in slopes with different geometry,surcharge,interstitial pressure,and pseudo-static load.

关键词： slopes stability planar failure variational calculus numerical methods

Mesoscopic model for binary fluids

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Frontiers of physics 2017年第5期12卷 231-239页

作者： C. Echeverria K. Tucci O. Alvarez-Llamoza E. E. Orozco-Guillén5 M. Morales M. G. Cosenza CeSiMo Universidad de Los Andes Mérida 5251 Mérida Venezuela Grupo de Caos y Sistemas Complejos Centro de Fisica Fundamental Universidad de Los Andes Mérida Venezuela Departamento de Fisica FACYT Universidad de Carabobo Valencia Venezuela Facultad de Ingenierla Universidad Católica de Cuenca Ecuador programa Académico de Ingenierla en Energla Universidad Politécnica de Sinaloa 82199 Mazatldn Mexico Programa Académico de Ingenierla en Nanoteenologla Universidad Politécnica de Sinaloa 82199 Mazatldn Mexico

We propose a model for studying binary fluids based on the mesoscopic molecular simulation technique known as multiparticle collision, where the space and state variables are continuous, and time is discrete. We include a repulsion rule to simulate segregation processes that does not require calculation of the interaction forces between particles, so binary fluids can be described on a mesoscopic scale. The model is conceptually simple and computationally efficient; it maintains Galilean invariance and conserves the mass and energy in the system at the micro- and macro-scale, whereas momentum is conserved globally. For a wide range of temperatures and densities, the model yields results in good agreement with the known properties of binary fluids, such as the density profile, interface width, phase separation, and phase growth. We also apply the model to the study of binary fluids in crowded environments with consistent results.

关键词： multiparticle collision dynamics mesoscopic models phase separation interface dynamics

Unexpected Metastatic Recurrent Myxofibrosarcoma: A Scenario That May Be More Common than You Think

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Surgical Science 2023年第11期14卷 667-672页

作者： Carrillo-Pinto Laura Cruz-Méndez Adriana Ucán-Gamboa Dioney Flores-López Alejandro Gutiérrez-Palma Ximena Facultad de Medicina Universidad Autónoma de Yucatán (UADY) Mérida México Department of General Surgery Clínica Hospital Mérida ISSSTE Mérida México Department of Radiology Clínica Hospital Mérida ISSSTE Mérida México

Soft tissue sarcomas represent only 1% of all adult cancers;myxofibrosarcoma is the most common type that arises in adult extremities, particularly lower limbs (77%), other less common locations are the trunk (12%) and neck (3%). Usually presenting as a painless, subcutaneous, slow growing mass with tendency for recurrence, they are prone to have higher histological grade and metastatic potential after recurrence;even in optimal multidisciplinary settings patients can have incomplete resections, making metastatic disease more common after misdiagnosis. We present the case of a 69-year-old male patient with a right infraescapular tumor, presenting as a painless 15 × 8 cm, mobile mass, with a slow but progressive growth, history of a previous tumor excised at the same location 5 years prior without histopathological report.

关键词： Case Report Myxofibrosarcoma Metastatic Disease Misdiagnosis

Transmission FTIR derivative spectroscopy for estimation of furosemide in raw material and tablet dosage form

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Acta Pharmaceutica Sinica B 2014年第5期4卷 376-383页

作者： Máximo Gallignani Rebeca A.Rondón JoséF.Ovalles María R.Brunetto Laboratorio de Espectroscopia Molecular Departamento de QuímicaFacultad de CienciasUniversidad de Los AndesMérida 5101-AVenezuela Departamento de Análisis y Control Facultad de Farmacia y BioanálisisUniversidad de Los AndesMérida 5101-AVenezuela

A Fourier transform infrared derivative spectroscopy(FTIR-DS)method has been developed for determining furosemide(FUR)in pharmaceutical solid dosage *** method involves the extraction of FUR from tablets with N,N-dimethylformamide by sonication and direct measurement in liquid phase mode using a reduced path length *** general,the spectra were measured in transmission mode and the equipment was configured to collect a spectrum at 4 cm^(-1) resolution and a 13 s collection time(10 scans co-added).The spectra were collected between 1400 cm^(-1) and 450 cm^(-1).Derivative spectroscopy was used for data processing and quantitative measurement using the peak area of the second order spectrum of the major spectral band found at 1165 cm^(-1)(SO_(2) stretching of FUR)with baseline *** method fulfilled most validation requirements in the 2 mg/mL and 20 mg/mL range,with a 0.9998 coefficient of determination obtained by simple calibration model,and a general coefficient of variation <2%.The mean recovery for the proposed assay method resulted within the(100±3)%over the 80%–120% range of the target *** results agree with a pharmacopoeial method and,therefore,could be considered interchangeable.

关键词： FTIR Derivative spectroscopy Furosemide Frusemide Pharmaceutical analysis

Effect of inductively coupled plasma surface treatment on silica gel and mesoporous MCM-41 particles

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Plasma Science and Technology 2018年第6期20卷 104-113页

作者： J A JUAREZ-MORENO U CHACON-ARGAEZ J BARRON-ZAMBRANO C CARRERA-FIGUEIRAS P QUINTANA-OWEN W TALAVERA-PECH Y PEREZ-PADILLA A AVILA-ORTEGA facultad de ingeniería química-uady periférico norte kilómetro 33.5col.chuburna de hidalgo inn C.P. 97203 Mérida Yucatan México centro de investigación y de estudios avanzados del ipn-unidad mérida km.6 antigua carretera a progreso apdo. Postal 73 Cordemex 97310 Méfida Yucatán México

Silica gel and MCM-41 synthesized mesoporous materials were treated with either oxygen（O_2）,hexamethyldisiloxane（HMDSO） and organic vapors like ethanol（Et OH）,and acrylonitrile（AN）inductive *** radiofrequency power for the modification was fixed to 120 W and30 min,assuring a high degree of organic ionization energy in the *** surface properties were studied by infrared spectroscopy（FTIR）,scanning electron microscopy,x-ray photoelectron spectroscopy and dynamic light scattering technique was used for characterizing size *** the silica and MCM-41 particles were modified by AN and HMDSO plasma gases,the surface morphology of the particles was changed,presenting another color,size or *** contrast,the treatments of oxygen and Et OH did not affect the surface morphology of both particles,but increased the oxygen content at the surface bigger than the AN and HMDSO plasma *** this study,we investigated the influence of different plasma treatments on changes in morphology and the chemical composition of the modified particles which render them a possible new adsorbent for utilization in sorptive extraction techniques for polar compounds.

关键词： silica MCM-41 nanoparticles plasma treatment

Assessment of Mg(OH)_(2)/TiO_(2) coating in the Mg-Ca-Zn alloy for improved corrosion resistance and antibacterial performance

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Journal of Magnesium and Alloys 2023年第1期11卷 361-378页

作者： Leonardo Hernández Jesús Ramón-Sierra Montserrat Soria-Castro Ángel Bacelis Geonel Rodríguez-Gattorno Elizabeth Ortiz-Vázquez Gloria Acosta Applied Physics Department Center for Research and Advanced Studies of the National Polytechnic Institute(CINVESTAV-IPN)Carr.Ant.a Progreso km.6C.P.97310MeridaYucatanMexico Tecnológico Nacional de México/Instituto Tecnológico de Mérida.Av.Tecnológico s/n Km.4.5 ant.Carr.Mérida-Progreso C.P.97118MéridaYucatánMéxico Facultad de Química Universidad Nacional Autónoma de México(UNAM)Av.Universidad 3000C.P.04510CoyoacánCDMXMéxico

The high activity of metallic magnesium and alloys limits its potential in biomedical applications;in recent years,extensive efforts have been devoted to modulating this *** this work,we present Mg(OH)_(2) and TiO_(2)barrier coatings to reduce the degradation of magnesium alloy(Mg-Ca-Zn)*** coatings were deposited by the anodization method and the spin-coating technique,*** anodized layer was coated with TiO_(2)generated from the hydrolysis of 3%weight of TTIP(Ti[OCH(CH_(3))_(2)]_(4),Titanium(IV)isopropoxide)in 2-Propanol deposited by the spin-coating *** the degradation in Ringer’s solution by electrochemical impedance spectroscopy and OCP revealed a 98%reduction in pittings in uncoated samples after 14 days of *** p H measurements revealed that the TiO_(2)coating reduced the alkalization of the physiological environment,keeping the pH at 6.0 *** vitro studies of two types of bacteria(*** and ***)exhibited zones of inhibition in the agar and activity bactericidal(kill time test).The mechanisms behind the improved degradation resistance and enhanced antibacterial activity are presented and discussed *** modification with Mg(OH)_(2)/TiO_(2)coatings is a promising strategy to control the biodegradation of magnesium implants for bone regeneration.

关键词： Magnesium alloy EIS Mg(OH)_(2) TiO_(2) Antibacterial coatings

Contrasting initial events of localized corrosion on surfaces of 2219-T42 and 6061-T6 aluminum alloys exposed in Caribbean seawater

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Transactions of Nonferrous Metals Society of China 2019年第1期29卷 34-42页

作者： Gloria ACOSTA Lucien VELEVA Juan Luis LóPEZ D.A.LóPEZ-SAURI Applied Physics Department Research Center for Advanced Studies (CINVESTAV) Unidad Mérida Tecnológico Nacional de México Instituto Tecnológico de Mérida Departamento de Química y Bioquímica

Aluminum alloy samples, 6061-T6 and 2219-T42, were exposed to Caribbean seawater for 90 d. The fluctuations of open circuit potential, considered as electrochemical noise (EN), were used to characterize and compare initial pitting events, which appeared on their surfaces. EN analysis was carried out using the power spectral density (PSD) vs frequency. The decrease of the β exponent in PSD graphs indicated a release of spontaneous energy with the progress of pit formation in seawater. The fluctuations were associated with the breakdown and formation of new corrosion layers. The values of β exponent in PSD graphs suggest that corrosion process of AA2219-T42 alloy occurs as a persistent non-stationary process, the dynamics of which is controlled by fractional Brownian motion (fBm), while on AA6061-T6 alloy the corrosion process was dominated by stationary and weakly persistent features, with the contribution of fractional Gaussian noise (fGn). After the exposure in seawater, SEM-EDX analysis revealed insoluble intermetallic particles on the alloys, rich in Cu or Fe and irregularly distributed. The preferential dissolution of Mg and Al occurs from the S-phase (Al2CuMg) of AA2219-T42 alloy.

关键词： aluminum alloy corrosion electrochemical noise intermetallic particles seawater

Reagent-free determination of amikacin content in amikacin sulfate injections by FTIR derivative spectroscopy in a continuous flow system

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Journal of Pharmaceutical Analysis 2014年第2期4卷 125-131页

作者： José F.Ovalles Máximo Gallignani María R.Brunetto Rebeca A.Rondón Carlos Ayala Departamento de Análisis y Control Facultad de Farmacia y BioanálisisUniversidad de Los AndesMérida 5101AVenezuela Laboratorio de Espectroscopia Molecular Departamento de QuímicaFacultad de CienciasUniversidad de Los AndesMérida 5101AVenezuela

The quantitative estimation of amikacin （AMK） in AMK sulfate injection samples is reported using FTIR-derivative spectrometric method in a continuous flow system. Fourier transform of mid-IR spectra were recorded without any sample pretreatment. A good linear calibration （r40.999, %RSDo 2.0） in the range of 7.7-77.0 mg/mL was found. The results showed a good correlation with the manufacturer＇s and overall they all fell within acceptable limits of most pharmacopoeial monographs on AMK sulfate.

关键词： Amikacin FlrIR derivative spectro-metry Continuous flow system Pharmaceuticalpreparation Injection Sulfate

The Contradiction between Two Versions of Quantum Theory Could Be Decided by Experiment

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Journal of Modern Physics 2019年第10期10卷 1190-1208页

作者： María Esther Burgos Faculty of Sciences University of Los Andes Mérida Venezuela

The incompatibility of Orthodox Quantum Mechanics with philosophical realism poses a serious challenge to scientists upholding such a philosophical doctrine. The desire to find a solution to this and other conceptual problems that quantum mechanics confronts has motivated many authors to propose alternative versions to Orthodox Quantum Mechanics. One of them is the Spontaneous Projection Approach, a theory grounded on philosophical realism. It has been introduced in previous papers and, with a few exceptions, it yields experimental predictions coincident with those of Orthodox Quantum Mechanics. One of these exceptions is analyzed in detail. The difference in predictions becomes apparent in a suggested experiment which could put both theories to the test.

关键词： Philosophical Realism Orthodox Quantum Mechanics Spontaneous Projection Approach Quantum Measurement Problem