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        • KCI등재

          Production of poorly crystalline tricalcium phosphate nanopowders using different mechanochemical reactions

          Bahman,Nasiri-Tabrizi,Abbas,Fahami 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

          Poorly crystalline nano-sized tricalcium phosphate powders were successfully synthesized by two distinct mechanochemical reactions. Results revealed that the structural features as well as morphological characteristics were influenced by the chemical composition of reagents. The obtained nanopowders exhibited average sizes about 21 and 28 nm. According to the TEM/SEM observations, the synthesized powders showed cluster-like structures composed of spheroidal particles with a mean size of about 23 nm and ellipsoidal particles with an average size of about 30 nm. The proposed method as a new vision in powder technology can be used for mass production of nanostructured tricalcium phosphates.

        • KCI등재후보

          Evaluation of the Antioxidant Capacity and Phenolic Content of Three Thymus Species

          Bahman,Nickavar,Naser,Esbati 사단법인약침학회 2012 Journal of Acupuncture & Meridian Studies Vol.5 No.3

          Thymus species are known to have significant amounts of phenolic and flavonoid compounds and exhibit strong antioxidant activities. This work was designed to evaluate the antioxidant activities of three endemic Iranian Thymus species (including T. daenensis, T. kotschyanus and T. pubescens) in different test systems (namely DPPH•, ABTS•+ and linoleic acid/β-carotene bleaching assays), to determine the total phenolic and flavonoid contents of the species (assayed by colorimetric techniques) and to study the possible composition-activity relationship. All the tested plants exhibited concentration-dependent antioxidant and free radical scavenging activities. T. pubescens showed the highest free radical scavenging activities in both DPPH• and ABTS•+ methods, while T. daenensis and T. kotschyanus were the most active species in the β-carotene bleaching inhibition test. On the other hand, T. pubescens exhibited a significantly higher level of the total flavonoid content compared with those of the other species, while no significant statistically differences were found among the tested plants regarding the total phenolic content. In addition, significant correlations were found between the flavonoid content and DPPH•/ABTS•+ radical scavenging activities, but not between the β-carotene bleaching inhibition system and the flavonoid content.

        • KCI등재SCOPUS

          Evaluation and Optimization of Factors Affecting the Performance of a Flow-through System Based on Immobilized Acetylcholineesterase as a Biosensor

          Bahman,Ebrahimi,Seyed,Abbas,Shojaosadati,Seyyed,Mohammad,Mousavi 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.3

          A flow-through system based on acetylcholineesterase (AChE) was studied. The system was prepared by mixing AChE and a multiwall carbon nanotube (MWCNT). Two important parameters, the ratios of AChE:MWCNT (X1) and AChE-MWCNT:sol-gel (X2)were optimized using response surface methodology. The results revealed that an enzyme immobilized within the MWCNT-sol-gel was more effective compared to one conducted with sol-gel. The optimum feed flow rate was 0.4 mL/min and ATChI concentration was found to be 1 mM. The optimum ratios of X1 and X2 for immobilization on ceramic packing were 1.07 and 0.43, respectively. The sensitivity of this flow-through system was 1.82 × 10−5/μM and long-term stability analyzed after 120 days was 74% of initial absorbance. With respect to an incubation time of 14 min, the detection limit for paraoxon was 7.3 × 10−12 mol.

        • SCIESCOPUSKCI등재
        • KCI등재SCOPUS

          Optimal Design of MR Damper Based on Tuning Bouc-Wen Model Parameters Using Hybrid Algorithms

          Bahman,Farahmand,Azar,Hedayat,Veladi,Siamak,Talatahari,Farzad,Raeesi 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.3

          This paper presents a useful approach to optimally design magnetorheological (MR) dampers used in structural buildings. To fulfill this aim, damper parameters are regarded as the design variables whose values can be obtained through an optimization process. To improve the quality of searching for the optimum parameters of MR dampers, charged system search (CSS) and grey wolf (GW) algorithms, two of the most widely utilized meta-heuristic algorithms, are used together, and hybrid CSS-GW is presented. To show the authenticity and robustness of the new algorithm in solving optimization problems, some benchmark test functions are tested, at first. Then, an eleven-story benchmark building equipped with 3 MR dampers is considered to get the optimum design of the MR damper using the hybrid CSS-GW. Results show that the developed hybrid algorithm can successfully figure out the optimum parameters of the MR dampers.

        • KCI등재SCOPUS

          Macropored microparticles with a core–shell architecture for oral delivery of biopharmaceuticals

          Bahman,Homayun,Ankit,Kumar,Priscila,T.,H.,Nascimento,Hyo-Jick,Choi 대한약학회 2018 Archives of Pharmacal Research Vol.41 No.8

          Microparticles (MPs) have been extensivelyresearched as a potential drug delivery vehicle. Here, weinvestigated the fabrication of MPs with pH-responsivemacropores and evaluated their potential applicability indeveloping solid oral drug formulations. Our previousstudy showed that macropored MPs, made of EudragitL100-55, could encapsulate 100 nm, 1 lm, and 4 lm sizedfluorescent beads—model drugs that are mimicking vaccines,bacteria, and cells. In the present study, closed-poredMPs after freeze-drying were coated with a gastric solubleEudragit EPO layer to protect MPs in the simulatedpregastric environment. Subsequently, drug encapsulatedMPs maintained their intact closed-pored structure in thesimulated gastric environment and exhibited a rapid releasein the simulated intestine environment. Our MP system wasfound to provide a significantly higher level of protectionto the encapsulated lactase enzyme compared to the controlsample (i.e. without using MPs). Real-time fluorescencemicroscopy analysis showed that macropored MPs releasedencapsulated drugs in a burst-release pattern and in a sizeindependentmanner. This work shows that our proposedEPO-coated MPs with pH-responsive macropores can meetthe challenges posed by the multiple physiological environmentsof the digestive tract and be used in developinghighly effective solid oral drug/vaccine formulations.

        • KCI등재SCOPUS

          An efficient simulation method for reliability analysis of systems with expensive-to-evaluate performance functions

          Bahman,Farahmand,Azar,Ali,Hadidi,Amin,Rafiee 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.5

          This paper proposes a novel reliability analysis method which computes reliability index, most probable point and probability of failure of uncertain systems more efficiently and accurately with compared to Monte Carlo, first-order reliability and response surface methods. It consists of Initial and Simulation steps. In Initial step, a number of space-filling designs are selected throughout the variables space, and then in Simulation step, performances of most of samples are estimated via interpolation using the space-filling designs, and only for a small number of the samples actual performance function is used for evaluation. In better words, doing so, we use a simple interpolation function called “reduced” function instead of the actual expensive-to-evaluate performance function of the system to evaluate most of samples. By using such a reduced function, total number of evaluations of actual performance is significantly reduced; hence, the method can be called Reduced Function Evaluations method. Reliabilities of six examples including series and parallel systems with multiple failure modes with truncated and/or non-truncated random variables are analyzed to demonstrate efficiency, accuracy and robustness of proposed method. In addition, a reliabilitybased design optimization algorithm is proposed and an example is solved to show its good performance.

        • KCI등재SCOPUS

          Simulation of reactive precipitation processes using the network-of-zones model

          Bahman,ZareNezhad 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.6

          2-D network-of-zones model is extended and applied to a reactive precipitation process in batch mode.The simulations are performed for a network of size 2(1010) for an elementary reaction through the solution of1400 ODEs. The complicated interactions between mixing efficacy and the system kinetics are systematically investi-gated. When the stirrer speed is very slow, the crystal size distribution (CSD) of the product in the precipitator is de-termined by the intensity of mixing. Conversely, at higher stirrer speed, the CSD is controlled by the system kinetics.More effective mixing leads to an increase in the number of crystals, a reduction of the average size and a narrowercrystal size distribution. The extended network-of-zones model presented in this work can be used conveniently forintegrating computational fluid dynamics and reactive precipitation processes.

        • KCI등재SCOPUS

          Seismic Performance of Composite RCS Special Moment Frames

          Bahman,Farahmand,Azar,Hosein,Ghaffarzadeh,Nima,Talebian 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.2

          Composite Reinforced Concrete-Steel (RCS) frames which consist of Reinforced Concrete (RC) columns and Steel (S) beams were represented to combine the advantages of pure RC and steel frames. This system permits the primary steel beam to run continuous through the reinforced concrete column. This paper evaluates seismic performance of RCS frames based on FEMA-356,considering plastic rotations as acceptance criteria. The effect of joint deformations on overall behavior of RCS frames is studied through nonlinear static analysis (Pushover) that is performed in OpenSees software. It is concluded that the RCS joint behavior increases lateral load capacity of frame. Additionally, 3 RC frames are compared to RCS frames with columns similar to those of RC frames. The results show a great improvement on overall behavior since steel beams is used instead of RC beams.

        • KCI등재

          A comparative study of hydroxyapatite nanostructures produced under different milling conditions and thermal treatment of bovine bone

          Bahman,Nasiri-Tabrizi,Abbas,Fahami,Reza,Ebrahimi-Kahrizsangi 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.1

          In the present investigation the effects of milling parameters (time, atmosphere, and media) andchemical composition of raw materials on the mechanochemical synthesis of nanocrystallinehydroxyapatite (n-HAp) were studied. For a comparative study of the mechanically activated samplesversus thermally treated specimen (natural origin), n-HAp was also produced via annealing of bovinebone at 800℃ for 2 h. The gained powders exhibited average sizes about 32 and 27 nm under airatmosphere, and about 32 and 34 nm under argon atmosphere. TEM images confirmed the formation ofn-HAp with various morphologies under different experimental conditions.

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