PREVENTION OF SINTERING DURING ANNEALING PROCESS OF FePt NANOPARTICLES COATED WITH ZnO SHELL

HOSSEIN ZEYNALI,HOSSEIN AKBARI,S. ARUMUGAM,ZOHREH CHAMANZADEH,G. KALAISELVAN,REYHANEH KARIMI GHASABEH 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6

Monodispersed 4.1 nm FePt nanoparticles with narrow size distribution were successfully synthesized by the chemical polyol process with co-reduction of Fe(acac)3 and Pt(acac)2 in the presence of 1,2-hexadecanediol as a reducing agent. To achieve hard ferromagnetic behavior with L10 phase and face center tetragonal (fct) structure, high temperature annealing is performed. Annealing causes the surfactant surrounding particles to decompose and agglomeration of particles occurs. In the present work, chemically synthesized FePt nanoparticles were coated with nonmagnetic ZnO oxide shell to prevent them from sintering. Coercivity of FePt and FePt/ZnO nanoparticles increases from 5 kOe to 10 kOe and 1.8 kOe to 6 kOe respectively, with the increasing annealing temperatures from 650 to 750?C.

Experimental evaluation of steel connections with horizontal slit dampers

Hossein Akbari Lor,Mohsen Izadinia,Parham Memarzadeh 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.32 No.1

This study introduces new connections that connect the beam to the column with slit dampers. Plastic deformations and damages concentrate on slit dampers. The slit dampers prevent plastic damages of column, beam, welds and panel zone and act as fuses. The slit dampers were prepared with IPE profiles that had some holes in the webs. In this paper, two experimental specimens were made. In first specimen (SDC1), just one slit damper connected the beam to the column and one IPE profile with no holes connected the bottom flange of the beam to the column. The second specimen (SDC2) had two similar dampers which connected the top and bottom flange of the beam to the column. Cyclic loading was applied on Specimens. The cyclic displacements conditions continued until 0.06 radian rotation of connection. The experimental observations showed that the bending moment of specimen SDC2 increased until 0.04 story drift. In specimen SDC1, the bending moment decreases after 0.03 story drift. Test results indicate the high performance of the proposed connection. Based on the results, the specimen with two slit damper (SDC2) has higher seismic performance and dissipates more energy in loading process than specimen SDC1. Theoretical formulas were extended for the proposed connections. Numerical studies have been done by ABAQUS software. The theoretical and numerical results had good agreements with the experimental data. Based on the experimental and numerical investigations, the high ductility of connection is obtained from plastic damages of slit dampers. The most flexural moment of specimen SDC1 occurred at 3% story drift and this value was 1.4 times the plastic moment of the beam section. This parameter for SDC2 was 1.73 times the plastic moment of the beam section and occurred at 4% story drift. The dissipated energy ratio of SDC2 to SDC1 is equal to 1.51.

Size control synthesis and high coercivity L10-FePt nanoparticles produced by iron (III) acetylacetonate salt

HOSSEIN ZEYNALI,HOSSEIN AKBARI,S. ARUMUGAM 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.23 No.-

Monodisperse 4.11 nm FePt nanoparticles were synthesized via chemical co-reduction of iron (III) acetylacetonate and platinum (II) acetylacetonate by 1,2-hexadecanediol as a reducing agent. Then through the seed mediated growth process smaller sized FePt nanoparticles are used as seeds for the growth of larger sized particles. There is no specific limitation to achieve upper size range by this method. In this work, we have successfully synthesized FePt nanoparticles up to 8.32 nm. After annealing these particles become ferromagnetic and their coercivirty increases with increasing particle sizes and reaches a maximum value of 17760 Oe for size of 8.32 nm.

Surface elasticity and size effect on the vibrational behavior of silicon nanoresonators

Hossein Nejat Pishkenari,Bahram Afsharmanesh,Ehsan Akbari 한국물리학회 2015 Current Applied Physics Vol.15 No.11

Predominance of nano-scale effects observed in material behavior at small scales requires implementation of new simulation methods which are not merely based on classical continuum mechanic. On the other hand, although the atomistic modeling methods are capable of modeling nano-scale effects, due to the computational cost, they are not suitable for dynamic analysis of nano-structures. In this research, we aim to develop a continuum-based model for nano-beam vibrations which is capable of predicting the results of molecular dynamics (MD) simulations with considerably lower computational effort. In this classical-based modeling, the surface and core regions are taken to have different mechanical properties, where core atoms are assumed to have macroscale properties whereas surface layer is showing a different elastic modulus from the core components. By estimating physical parameters of proposed classical model using molecular dynamics results and the genetic algorithm, calibrated classical EulereBernoulli and Timoshenko beam models are developed. The results demonstrates that a Timoshenko beam model incorporating surface effects and having calibrated parameters, is able to provide almost the same results as molecular dynamics method which can be used to predict the vibrational behavior of nano-beams at different scales from nano to macro.

Mixed-pairing superconductivity in 5d Mott insulators with antisymmetric exchange: Application to Sr2IrO4

Zare, Mohammad-Hossein,Biderang, Mehdi,Akbari, Alireza American Physical Society 2017 Physical Review B Vol.96 No.20

<P>We study the symmetry of the potential superconducting order parameter in 5d Mott insulators with an eye toward hole-doped Sr2IrO4. Using a mean-field method, a mixed singlet-triplet superconductivity, d + p, is observed due to the antisymmetric exchange originating from a quasi-spin-orbit coupling. Our calculation on ribbon geometry shows the possible existence of the topologically protected edge states, because of the nodal structure of the superconducting gap. These edge modes are spin polarized and emerge as zero-energy flat bands, supporting a symmetry-protected Majorana state, verified by evaluation of the winding number and Z(2) topological invariant. At the end, a possible experimental approach for observation of these edge states and determination of the superconducting gap symmetry is discussed based on the quasiparticle interference technique.</P>

Modeling and control of a flexible continuum module actuated by embedded shape memory alloys

Alireza Hadi,Hossein Akbari 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.4

Continuum manipulators as a kind of mechanical arms are useful tools in special robotic applications. In medical applications, like colonoscopy, a maneuverable thin and flexible manipulator is required. This research is focused on developing a basic module for such an application using shape memory alloys (SMA). In the structure of the module three wires of SMA are uniformly distributed and attached to the circumference of a flexible tube. By activating wires, individually or together, different rotation regimes are provided. SMA model is used based on Brinson work. The SMA model is combined to model of flexible tube to provide a composite model of the module. Simulating the model in Matlab provided a platform to be used to develop controller. Complex and nonlinear behavior of SMA make the control problem hard especially when a few SMA actuators are active simultaneously. In this paper, position control of the two degree of freedom module is under focus. An experimental control strategy is developed to regulate a desired position in the module. The simulation results present a reasonable performance of the controller. Moreover, the results are verified through experiments and show that the continuum module of this paper would be used in real modular manipulators.

Translation and Validation of the Activities of Daily Living Scale with Iranian Elderly Cancer Patients Treated in an Oncology Unit

Khoei, Mahtab Alizadeh,Akbari, Mohammad Esmail,Sharifi, Farshad,Fakhrzadeh, Hossein,Larijani, Bagher Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.5

Background: This study evaluated the validity and reliability of applying the Katz's Activities of Daily Living (ADL) scale in an Iranian sample of elderly oncologic patients following initial cancer treatment. Materials and Methods: The scale was translated with the forward-backward procedure to give an Iranian version. The ADL scale was then applied in a random sample of 400 oncologic patients aged 60 and older following initial cancer treatment. Assessment of the scale stability was twice, with a 14-days (two weeks) interval, to 30 (of the 400) eligible elderly cancer patients in March 2012. To measure treatment effects, the index was run with 150 patients in a three month recall, following oncology processing. Exploratory and confirmatory factor analysis was performed for assessment of construct validity of the Katz's ADL. Reliability was measured with internal consistency (Cronbach's alpha co-efficient), and test/retest (Spearman's r value) of the instrument. Criterion validity was evaluated by comparing the Katz with Physical Function (PF) subscale of SF 36. Known-group validity was approved by comparing of Katz' ADL between quartile groups of PF subscale of SF 36. Results: In our study the ADL demonstrated a high degree of internal homogeneity (Cronbach's alpha 0.923). There was a high correlation between scores of two time measurement of Katz's ADL (p value of two- related- samples test was 0.3). Construct validity showed a correlation coefficient of 0.572 between the ADL and PF scores. In factor analysis, 2 factors were extracted. Evidence for the reliability of the questionnaire was good and known group validity was approved by significant differences of ADL score between quartiles of the PF subscale of SF36. Conclusions: The results suggest that the Iranian version of ADL applied for oncologic older adult patients following initial cancer treatment is a reliable and a valid clinical instrument and comparable to those reported in other studies.

Poster Session : Biotechnology ; Isolation and characterization of follicule stimulating hormone alpha subunit gene

( Shabani Ali Akbar ),( Akbari Eidgahi Mohammad Reza ),( Nasr Reza ),( Hajighorbani Amir Hossein ) 한국생화학분자생물학회 (구 한국생화학회) 2007 생화학분자생물학회 춘계학술발표논문집 Vol.2007 No.-

The crack propagation of fiber-reinforced self-compacting concrete containing micro-silica and nano-silica

Moosa Mazloom,Amirhosein Abna,Hossein Karimpour,Mohammad Akbari-Jamkarani Techno-Press 2023 Advances in nano research Vol.15 No.6

In this research, the impact of micro-silica, nano-silica, and polypropylene fibers on the fracture energy of self-compacting concrete was thoroughly examined. Enhancing the fracture energy is very important to increase the crack propagation resistance. The study focused on evaluating the self-compacting properties of the concrete through various tests, including J-ring, V-funnel, slump flow, and T50 tests. Additionally, the mechanical properties of the concrete, such as compressive and tensile strengths, modulus of elasticity, and fracture parameters were investigated on hardened specimens after 28 days. The results demonstrated that the incorporation of micro-silica and nano-silica not only decreased the rheological aspects of self-compacting concrete but also significantly enhanced its mechanical properties, particularly the compressive strength. On the other hand, the inclusion of polypropylene fibers had a positive impact on fracture parameters, tensile strength, and flexural strength of the specimens. Utilizing the response surface method, the relationship between micro-silica, nano-silica, and fibers was established. The optimal combination for achieving the highest compressive strength was found to be 5% micro-silica, 0.75% nano-silica, and 0.1% fibers. Furthermore, for obtaining the best mixture with superior tensile strength, flexural strength, modulus of elasticity, and fracture energy, the ideal proportion was determined as 5% micro-silica, 0.75% nano-silica, and 0.15% fibers. Compared to the control mixture, the aforementioned parameters showed significant improvements of 26.3%, 30.3%, 34.3%, and 34.3%, respectively. In order to accurately model the tensile cracking of concrete, the authors used softening curves derived from an inverse algorithm proposed by them. This method allowed for a precise and detailed analysis of the concrete under tensile stress. This study explores the effects of micro-silica, nano-silica, and polypropylene fibers on self-compacting concrete and shows their influences on the fracture energy and various mechanical properties of the concrete. The results offer valuable insights for optimizing the concrete mix to achieve desired strength and performance characteristics.

Removal of strontium ions from nuclear waste using synthesized MnO2-ZrO2 nano-composite by hydrothermal method in supercritical condition

Seyed Javad Ahmadi,Neda Akbari,Zahra Shiri-Yekta,Mohammad Hossein Mashhadizadeh,Morteza Hosseinpour 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.3

This study focuses mainly on the synthesis of MnO2-ZrO2 nano-composite as a new inorganic adsorbent. Supercritical water was used as a preparation medium for particle deposited materials. MnO2-ZrO2 was prepared frommetal nitrate solutions in supercritical region. The resulting sample was characterized by Fourier transform infrared(FTIR), X-ray fluorescence (XRF), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and transmissionelectron microscope (TEM). Analyses of the TEM images show the possibility for crystallizing nano-sized particles. The synthesized adsorbent was then used for the removal of strontium(II) from the nuclear waste. Moreover, anumber of factors such as aqueous phase pH, contact time and initial metal ions concentration in the adsorption processwere investigated. Comparison of the adsorption efficiency of the MnO2-ZrO2 nano-particles with those of thenon-nano particles shows a shift of uptake of the metal ions vs. pH curves towards lower pH values and a significantimprovement in adsorption of strontium ions was observed by using the nano-adsorbent. The kinetic data correspondswell to the pseudo-second-order equation. The adsorption data for strontium(II) were well fitted by the Langmuir isotherm. The synthesized nano-composite also showed a strong affinity toward the removal of Y(III), Ni(II), Pb(II) andCo(II) from the nuclear radioactive waste.