Effect of calcination and reaction conditions on the catalytic performance of Co–Ni/Al2O3 catalyst for CO hydrogenation

Akbar Zare,Mehdi Shiva,Ahad Zare,Ali Akbar Mirzaei 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.6

The Co–Ni/Al2O3 catalysts prepared using impregnation procedure, were used for the Fischer–Tropsch synthesis. The effect of calcination conditions of the catalyst as well as reactor situation was studied. It was found that the catalyst calcined at 550 8C for 6 h in air atmosphere has shown the best catalytic performance for CO hydrogenation. The best operational conditions were obtained as following:T = 350 8C, P = 1 atm and H2/CO = 2/1.

Development and modification of conventional Ouali model for tensile modulus of polymer/carbon nanotubes nanocomposites assuming the roles of dispersed and networked nanoparticles and surrounding interphases

Zare, Yasser,Rhee, Kyong Yop Academic Press 2017 Journal of Colloid and Interface Science Vol. No.

<P><B>Abstract</B></P> <P>In this paper, conventional Ouali model for tensile modulus of composites is developed for polymer/carbon nanotubes (CNT) nanocomposites (PCNT) assuming the influences of filler network and dispersed nanoparticles above percolation threshold as well as the interphases between polymer host and nanoparticles which reinforce the nanocomposite and facilitate the networking. The developed model is simplified, because the characteristics of dispersed nanoparticles and surrounding interphase cannot significantly change the modulus of PCNT. The suggested model is compared to the experimentally measured modulus of some samples, which can calculate the percolation threshold of interphase regions and the possessions of interphase and filler network. The suggested model correctly predicts the influences of all parameters on the modulus. Thinner and longer CNT in addition to thicker interphase enhance the volume fraction of interphase which shifts the connectivity of interphase regions to smaller nanoparticle fraction and improves the modulus of PCNT. A very low level of percolation threshold significantly develops the modulus, but its high ranges have not any role. Among the studied parameters, the thickness and modulus of interphase between polymer host and networked nanoparticles play the most important roles in the modulus of PCNT.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Robustness of optimized FPID controller against uncertainty and disturbance by fractional nonlinear model for research nuclear reactor

Zare, Nafiseh,Jahanfarnia, Gholamreza,Khorshidi, Abdollah,Soltani, Jamshid Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.9

In this study, a fractional order proportional integral derivative (FOPID) controller is designed to create the reference power trajectory and to conquer the uncertainties and external disturbances. A fractional nonlinear model was utilized to describe the nuclear reactor dynamic behaviour considering thermal-hydraulic effects. The controller parameters were tuned using optimization method in Matlab/Simulink. The FOPID controller was simulated using Matlab/Simulink and the controller performance was evaluated for Hard variation of the reference power and compared with that of integer order a proportional integral derivative (IOPID) controller by two models of fractional neutron point kinetic (FNPK) and classical neutron point kinetic (CNPK). Also, the FOPID controller robustness was appraised against the external disturbance and uncertainties. Simulation results showed that the FOPID controller has the faster response of the control attempt signal and the smaller tracking error with respect to the IOPID in tracking the reference power trajectory. In addition, the results demonstrated the ability of FOPID controller in disturbance rejection and exhibited the good robustness of controller against uncertainty.

The Effect of Occupational Noise Exposure on Serum Cortisol Concentration of Night-shift Industrial Workers: A Field Study

Zare, Sajad,Baneshi, Mohammad R.,Hemmatjo, Rasoul,Ahmadi, Saeid,Omidvar, Mohsen,Dehaghi, Behzad F. Occupational Safety and Health Research Institute 2019 Safety and health at work Vol.10 No.1

Background: In both developed and developing countries, noise is regarded as the most common occupational hazard in various industries. The present study aimed to examine the effect of sound pressure level (SPL) on serum cortisol concentration in three different times during the night shift. Methods: This case-control study was conducted among 75 workers of an industrial and mining firm in 2017. The participants were assigned to one of the three groups (one control and two case groups), with an equal number of workers (25 participants) in each group. Following the ISO 9612 standard, dosimetry was adopted to evaluate equivalent SPL using a TES-1345 dosimeter. The influence of SPL on serum cortisol concentration was measured during the night shift. The serum cortisol concentration was measured using a radioimmunoassay (RIA) test in the laboratory. Repeated measure analysis of variance and linear mixed models were used with ${\alpha}=0.05$. Results: The results indicated a downward trend in the serum cortisol concentration of the three groups during the night shift. Both SPL and exposure time significantly affected cortisol concentration (p < 0.0001, p < 0.0001). Conversely, age and body mass index had no significant influence on cortisol concentration (p = 0.360, p = 0.62). Conclusion: Based on the obtained results, increasing SPL will lead to enhancement of serum cortisol concentration. Given that cortisol concentration varies while workers are exposed to different SPLs, this hormone can be used as a biomarker to study the effect of noise-induced stress.

Expansion of Kolarik model for tensile strength of polymer particulate nanocomposites as a function of matrix, nanoparticles and interphase properties

Zare, Yasser,Rhee, Kyong Yop Academic Press 2017 Journal of Colloid and Interface Science Vol. No.

<P><B>Abstract</B></P> <P>Kolarik proposed a model for tensile strength of polymer particulate composites based on the cubic orthogonal skeleton or three perpendicular plates (3PP) system. In this paper, Kolarik model is expanded for tensile strength of polymer nanocomposites containing spherical nanoparticles assuming the interphase properties. This model expresses the strength as a function of interphase properties. This development is performed using some models such as Pukanszky and Nicolais-Narkis. The expanded model is applied to calculate the thickness and strength of interphase by the experimental results. Furthermore, the strength of polymer nanocomposites is evaluated at different levels of material and interphase properties. The experimental data show good agreement with the predictions of the developed model.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Assessing Misdiagnosis of Relapse in Patients with Gastric Cancer in Iran Cancer Institute Based on a Hidden Markov Multi-state Model

Zare, Ali,Mahmoodi, Mahmood,Mohammad, Kazem,Zeraati, Hojjat,Hosseini, Mostafa,Naieni, Kourosh Holakouie Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.9

Background: Accurate assessment of disease progression requires proper understanding of natural disease process which is often hidden and unobservable. For this purpose, disease status should be clearly detected. But in most diseases it is not possible to detect such status. This study, therefore, aims to present a model which both investigates the unobservable disease process and considers the error probability in diagnosis of disease states. Materials and Methods: Data from 330 patients with gastric cancer undergoing surgery at the Iran Cancer Institute from 1995 to 1999 were analyzed. Moreover, to estimate and assess the effect of demographic, diagnostic and clinical factors as well as medical and post-surgical variables on transition rates and the probability of misdiagnosis of relapse, a hidden Markov multi-state model was employed. Results: Classification errors of patients in alive state without a relapse ($e_{21}$) and with a relapse ($e_{12}$) were 0.22 (95% CI: 0.04-0.63) and 0.02 (95% CI: 0.00-0.09), respectively. Only variables of age and number of renewed treatments affected misdiagnosis of relapse. In addition, patient age and distant metastasis were among factors affecting the occurrence of relapse (state1${\rightarrow}$state2) while the number of renewed treatments and the type and extent of surgery had a significant effect on death hazard without relapse (state2${\rightarrow}$state3)and death hazard with relapse (state2${\rightarrow}$state3). Conclusions: A hidden Markov multi-state model provides the possibility of estimating classification error between different states of disease. Moreover, based on this model, factors affecting the probability of this error can be identified and researchers can be helped with understanding the mechanisms of classification error.

Association of Amplitude and Stability of Circadian Rhythm, Sleep Quality, and Occupational Stress with Sickness Absence among a Gas Company Employees-A Cross Sectional Study from Iran

Zare, Rezvan,Choobineh, Alireza,Keshavarzi, Sareh Occupational Safety and Health Research Institute 2017 Safety and health at work Vol.8 No.3

Background: The present study was carried out to assess the relationship between sickness absence and occupational stress, sleep quality, and amplitude and stability of circadian rhythm as well as to determine contributing factors of sickness absence. Methods: This cross sectional study was conducted on 400 randomly selected employees of an Iranian gas company. The data were collected using Pittsburgh sleep quality index, Karolinska sleepiness scale, circadian type inventory, and Osipow occupational stress questionnaires. Results: The mean age and job tenure of the participants were $33.18{\pm}5.64years$ and $6.06{\pm}4.99years$, respectively. Also, the participants had been absent from work on average 2.16 days a year. According to the results, 209 participants had no absences, 129 participants had short-term absences, and 62 participants had long-term absences. The results showed a significant relationship between short-term absenteeism and amplitude of circadian rhythm [odds ratio (OR) = 6.13], sleep quality (OR = 14.46), sleepiness (OR = 2.08), role boundary (OR = 6.45), and responsibility (OR = 5.23). Long-term absenteeism was also significantly associated with amplitude of circadian rhythm (OR = 2.42), sleep quality (OR = 21.56), sleepiness (OR = 6.44), role overload (OR = 4.84), role boundary (OR = 4.27), and responsibility (OR = 3.72). Conclusion: The results revealed that poor sleep quality, amplitude of circadian rhythm, and occupational stress were the contributing factors for sickness absence in the study population.

Accounting the reinforcing efficiency and percolating role of interphase regions in tensile modulus of polymer/CNT nanocomposites

Zare, Yasser,Rhee, Kyong Yop Elsevier 2017 European polymer journal Vol.87 No.-

<P><B>Abstract</B></P> <P>In this work, a micromechanics model is developed for tensile modulus that incorporates the reinforcing efficiency and percolating effects of the interphase in polymer/CNT nanocomposites (PCNT). More specifically, Takayanagi model is developed to account interphases around dispersed and networked nanoparticles. The interphase percolation is considered in the model by the thickness of the interphase, as well as the radius and length of CNT, which can affect the percolation threshold of nanoparticles and concentration of the filler network. The validity of the developed model is evaluated by some experimental results. Similarly, the effects of all parameters attributed to dispersed and networked nanoparticles as well as interphases on the modulus of PCNT are studied. Based on the developed model, the high values of some parameters such as interphase thickness, interphase modulus between the polymer matrix and networked nanoparticles, network modulus, fraction of nanoparticles in the network, and network density improve the modulus of PCNT, whereas the radius and percolation threshold of nanoparticles have an adverse effect.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The reinforcing efficiency and percolating effect of interphase in PCNT are studied. </LI> <LI> The interphases around the dispersed and networked nanoparticles are accounted. </LI> <LI> The interphase percolation is considered by thickness of interphase and CNT dimensions. </LI> <LI> The validity of the developed model is evaluated by the experimental results. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Structural and phase separation characterization of poly(lactic acid)/poly(ethylene oxide)/carbon nanotube nanocomposites by rheological examinations

Zare, Yasser,Garmabi, Hamid,Rhee, Kyong Yop Elsevier 2018 Composites Part B, Engineering Vol.144 No.-

<P><B>Abstract</B></P> <P>The morphology and phase separation have significant impacts on the properties and applications of polymer blends and nanocomposites. In this study, poly(lactic acid) (PLA)/poly(ethylene oxide) (PEO) blends and PLA/PEO/carbon nanotube (CNT) nanocomposites are prepared by solution mixing and the rheological approach is applied to study the morphology and phase separation of the prepared samples. Scanning electron microscopy (SEM) is also used to study the morphology and structure of samples. Additionally, the miscibility or immiscibility between polymer blends was analyzed through Han plots. The results display the lower critical solution temperature (LCST) phase diagram for the prepared samples demonstrating that the enhancement of temperature promotes phase separation. Moreover, the addition of nanoparticles transfers the LCST diagram to high temperatures. The deformation relaxation of PEO droplets commonly diminishes the modulus at very low frequencies, while the formation of big CNT networks in nanocomposites containing high CNT content results in a constant modulus. Han plots also represent the immiscibility in the samples containing 60 and 75 wt% PLA and the nanocomposites including 90 wt% PLA show homogenous structures. The SEM images verify the outputs of rheological tests conducted for the morphology of samples.</P>

Expression of normal stress difference and relaxation modulus for ternary nanocomposites containing biodegradable polymers and carbon nanotubes by storage and loss modulus data

Zare, Yasser,Rhee, Kyong Yop Elsevier Science Ltd 2019 Composites Part B, Engineering Vol.158 No.-

<P><B>Abstract</B></P> <P>In this paper, the first normal stress differences (N<SUB>1</SUB>) and the relaxation modulus (G (t)) are predicted for prepared poly (lactic acid) (PLA)/poly (ethylene oxide) (PEO)/carbon nanotubes (CNT) nanocomposites using the experimental results of storage and loss moduli. N<SUB>1</SUB> and G (t) are calculated for these samples as a function of shear rate. Moreover, the effects of various parameters on N<SUB>1</SUB> and G (t) are revealed to validate the equations. N<SUB>1</SUB> increases by shear rate, but it shows a plateau at low shear rates. The addition of nanoparticles to the blends increases N<SUB>1</SUB> demonstrating that the nanoparticles enhance the elasticity. G (t) decreases upon increasing in the shear rate in all samples and the addition of CNT to polymer blends causes a high G (t). A high storage modulus and small loss modulus enhance N<SUB>1</SUB> and G (t), whereas poor storage modulus lowers N<SUB>1</SUB> and G (t). Additionally, G (t) improves significantly at small strain and high N<SUB>1</SUB>. This work presents useful guidelines for calculation of N<SUB>1</SUB> and G (t) and understanding the origin of these terms in polymer systems.</P>