Modeling of neutron diffractometry facility of Tehran Research Reactor using Vitess 3.3a and MCNPX Codes

Z. Gholamzadeh, E. Bavarnegin,E. Bavarnegin,M.Lamehi Rachti,S.M. Mirvakili,M.H.Choopan Dastjerdi,H. Ghods,A. Jozvaziri,M. Hosseini 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1

The neutron powder diffractometer (NPD) is used to study a variety of technologically important andscientifically driven materials such as superconductors, multiferroics, catalysts, alloys, ceramics, cements,colossal magnetoresistance perovskites, magnets, thermoelectrics, zeolites, pharmaceuticals,etc. Monte Carloebased codes are powerful tools to evaluate the neutronic behavior of the NPD. In thepresent study, MCNPX 2.6.0 and Vitess 3.3a codes were applied to simulate NPD facilities, which couldbe equipped with different optic devices such as pyrolytic graphite or neutron chopper. So, the MonteCarloebased codes were used to simulate the NPD facility of the 5 MW Tehran Research Reactor. Thesimulation results were compared to the experimental data. The theoretical results showed goodconformity to experimental data, which indicates acceptable performance of the Vitess 3.3a code in theneutron optic section of calculations. Another extracted result of this work shows that application ofneutron chopper instead of monochromator could be efficient to keep neutron flux intensity higherthan 106 n/s/cm2 at sample position.

A Comparison between Three Numerical Criteria for Prediction the Forming Limit Diagram of St14 Steel

M. Moslemi,S.J. Hosseinipour,M.E. Hosseini,A.H. Gorji 한국소성가공학회 2011 기타자료 Vol.2011 No.8

In this paper, the forming limit diagram (FLD) of a low carbon steel St14 (DIN 1623) is investigated experimentally and numerically. The objective of this study is to find a numerical criterion which enables a simple and reliable determination of the FLD. For this purpose, Out-of-plane stretching test method with hemispherical punch was simulated by using commercial finite element software, ABAQUSE 6.9. One-quarter of the geometry was used due to symmetry. The material was modeled as elastoplastic and the anisotropic properties were described by the Hill quadratic yield criterion. The model was assumed to be rate independent. Coulomb friction law was defined for all contact surfaces. The simulation process was performed in two steps. In the first step the blank-holder moves down and deforms the blank into the draw-bead. Then the punch moves up at 20 increments and deforms the specimen to a specified displacement. Three numerical criteria including maximum second thickness strain derivative (CRIT1), equivalent plastic strain increment ratio (CRIT2), and total equivalent plastic strain ratio (CRIT3) were evaluated and the forming limit curve (FLC) were obtained. The predicted FLC were compared with experimental data. Unlike the CRIT2, the CRIT1 and CRIT3 were in good agreements with were experimental data. The CRIT1 criterion predicted the lower bound of the experimental results. While by using the CRIT3 criterion both the lower and upper bounds of the experimental results were predicted.

Nonlinear vibration analysis of an electrostatically excited micro cantilever beam coated by viscoelastic layer with the aim of finding the modified configuration

E. Poloei,M. Zamanian,S.A.A. Hosseini 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.61 No.2

In this study, the vibration of an electrostatically actuated micro cantilever beam is analyzed in which a viscoelastic layer covers a portion of the micro beam length. This proposed model is considered as the main element of mass and pollutant micro sensors. The nonlinear motion equation is extracted by means of Hamilton principle, considering nonlinear shortening effect for Euler-Bernoulli beam. The non-linear effects of electrostatic excitation, geometry and inertia have been taken into account. The viscoelastic model is assumed as Kelvin-Voigt model. The motion equation is discretized by Galerkin approach. The linear free vibration mode shapes of non-uniform micro beam i.e. the linear mode shape of the system by considering the geometric and inertia effects of viscoelastic layer, have been employed as comparison function in the process of the motion equation discretization. The discretized equation of motion is solved by the use of multiple scale method of perturbation theory and the results are compared with the results of numerical Runge-Kutta approach. The frequency response variations for different lengths and thicknesses of the viscoelastic layer have been founded. The results indicate that if a constant volume of viscoelastic layer is to be deposited on the micro beam for mass or gas sensor applications, then a modified configuration may be found by using the analysis of this paper.

Cellular normoxic biophysical markers of hydroxyurea treatment in sickle cell disease

Hosseini, Poorya,Abidi, Sabia Z.,Du, E,Papageorgiou, Dimitrios P.,Choi, Youngwoon,Park, YongKeun,Higgins, John M.,Kato, Gregory J.,Suresh, Subra,Dao, Ming,Yaqoob, Zahid,So, Peter T. C. National Academy of Sciences 2016 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.113 No.34

<P>Hydroxyurea (HU) has been used clinically to reduce the frequency of painful crisis and the need for blood transfusion in sickle cell disease (SCD) patients. However, the mechanisms underlying such beneficial effects of HU treatment are still not fully understood. Studies have indicated a weak correlation between clinical outcome and molecular markers, and the scientific quest to develop companion biophysical markers have mostly targeted studies of blood properties under hypoxia. Using a common-path interferometric technique, we measure biomechanical andmorphological properties of individual red blood cells in SCD patients as a function of cell density, and investigate the correlation of these biophysical properties with drug intake as well as other clinically measured parameters. Our results show that patient-specific HU effects on the cellular biophysical properties are detectable at normoxia, and that these properties are strongly correlated with the clinically measured mean cellular volume rather than fetal hemoglobin level.</P>

Novel composite graphene oxide/chitosan nanoplates incorporated into PES based nanofiltration membrane: Chromium removal and antifouling enhancement

E. Bagheripour,A.R. Moghadassi,S.M. Hosseini,B. Van der Bruggen,F. Parvizian 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.62 No.-

In this work, novel nanofiltration membranes with outstanding performance and antifouling properties were fabricated by incorporating composite graphene oxide/chitosan (GOC) nanoplates into the membrane structure. GOC composite nanoplates were prepared by surface modification of GO with chitosan. The GOC nanoplates were then introduced as additives in a polymeric phase in different concentrations (up to 1%) in view of membrane synthesis. these membranes were thoroughly characterized and assessed for their Na2SO4 and CrSO4 rejection and water flux. Furthermore, the antifouling performance of GO and GOC filled membranes in high concentration (1 wt%) was investigated. Modified membranes with addition of GOCs showed a higher hydrophilicity, pure water flux and rejection, and a smoother surface compared to a bare PES and a GO incorporated membrane. SEM surface images indicated a more uniformed distribution of GOCs at a high loading rate (1 wt%) compared to GO. Due to the uniform dispersion of GOCs, a better antifouling performance was observed than for GO filled membranes. The results indicate that surface modification of GO with chitosan can enhance the membrane performance and properties, due to availability of sites with higher activity.

A computational model of ureteral peristalsis and an investigation into ureteral reflux

G. Hosseini,C. Ji,D. Xu,M. A. Rezaienia,E. Avital,A. Munjiza,J. J. R. Williams,J. S. A. Green 대한의용생체공학회 2018 Biomedical Engineering Letters (BMEL) Vol.8 No.1

The aim of this study is to create a computationalmodel of the human ureteral system that accuratelyreplicates the peristaltic movement of the ureter for avariety of physiological and pathological functions. Theobjectives of this research are met using our in-house fluidstructuraldynamics code (CgLes–Y code). A realisticperistaltic motion of the ureter is modelled using a novelpiecewise linear force model. The urodynamic responsesare investigated under two conditions of a healthy and adepressed contraction force. A ureteral pressure during thecontraction shows a very good agreement with correspondingclinical data. The results also show a dependencyof the wall shear stresses on the contraction velocity and itconfirms the presence of a high shear stress at the proximalpart of the ureter. Additionally, it is shown that an inefficientlumen contraction can increase the possibility of acontinuous reflux during the propagation of peristalsis.

Adapting the release characteristics of aluminum phosphide from membrane-coated rice tablets by using activated carbon nanoparticles

S. Solhi,E. Jashni,S.M. Hosseini,B. Van der Bruggen,H. Solhi,A.R. Khodabakhshi 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.58 No.-

Membrane-coated tables were prepared to control the release rate of aluminum phosphide from rice tablets when this tablet comes into contact with water in the stomach. Mixed matrix polyvinyl chloride-co-activated carbon nanoparticles (ACNPs) membranes was used as a thin film to coat the rice tablets. The effect of ACNPs as additive in membrane matrix on release behavior of aluminum phosphide was evaluated. The scanning electron microscopy (SEM) images and X-ray diffraction patterns showed that nanoparticles are uniformly distributed in the prepared coatings. The membrane water contact angle was enhanced from 55° to 80° in the presence of ACNPs. The tear resistance of the prepared membranes was also improved from 4.34 to 5.01 (grf/mic) by using ACNPs. The membrane-coated tablets showed a controlled aluminum phosphide release rate compared to pristine rice tablet without cover. The fastest aluminum phosphide release rate for all samples is related to the first five days. In addition, the half-time and life-time of membrane-coated tablets were declined by an increase of the ACNPs ratio up to 15 wt%. Swelling of the fabricated cover in aqueous environment led to a decrease of the aluminum phosphide release rate.