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Saideh S. Mortazavi,David Chavez-Flores,James M. Salvador 한국생물공학회 2016 Biotechnology and Bioprocess Engineering Vol.21 No.5
The Candida rugosa lipase catalyzed Dynamic Kinetic Resolution of racemic ibuprofen methyl ester produced (S)-ibuprofen in over 90% yield within 72 h at pH 7.6. The best concentration of various buffers for these reactions ranged from 0.2 to 0.5 M. The commercial lipase was found to be acidic altering the final pH of the reaction mixtures. Dimethylformamide co-solvent maintained the reaction pH better than dimethylsulfoxide. Lower concentrations of ibuprofen methyl ester and higher stirring rates led to faster conversions. The minimal amount of lipase needed was 20 mg/mL buffer. Reaction of (R)-ibuprofen methyl ester under the optimized conditions excluding the lipase led to no racemization, indicating that the conversion of (R)-ibuprofen methyl ester to (S)-ibuprofen is catalyzed by the enzyme, thus, indicating Candida rugosa lipase possess Isomerase activity.
Mechanical Behavior of a New Biphasic Calcium Phosphate Bone Graft
S. M. Rabiee,S. M. J. Mortazavi,F. Moztarzadeh,D. Sharifi,Sh. Sharifi,M. Solati-Hashjin,H. Salimi-Kenari,D. Bizari 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.2
The aim of this study was to create a new porous calcium phosphate implant for use as a synthetic bone graft substitute. Porous bioceramic was fabricated using a foam-casting method. By using polyurethane foam and a slurry containing hydroxyapatite-dicalcium phosphate powder, water, and additives, a highly porous structure (66 ± 5%) was created. The porous specimens possess an elastic modulus of 330 ± 32 MPa and a compressive strength of 10.3 ± 1.7 MPa. The X-ray diffraction patterns show hydroxyapatite and beta-pyrophosphate phases after sintering. A rabbit model was developed to evaluate the compressive strength and elastic modulus of cancellous bone defects treated with these porous synthetic implants. The compressive mechanical properties became weaker until the second month post implantation. After the second month, these properties increased slightly and remained higher than control values. New bone formed on the outside surface and on the macropore walls of the specimens, as osteoids and osteoclasts were evident two months postoperatively. Considering these properties, these synthetic porous calcium phosphate implants could be applicable as cancellous bone substitutes.
Association of a Synthetic Bone Graft and Bone Marrow Cells as a Composite Biomaterial
S. M. Rabiee,S. M. J. Mortazavi,F. Moztarzadeh,D. Sharifi,F. Fakhrejahani,A. Khafaf,S. A. Houshiar Ahmadi,N. Nosoudi,R. Ravarian 한국생물공학회 2009 Biotechnology and Bioprocess Engineering Vol.14 No.1
Porous calcium phosphates have osteoconductive properties. The aim of this study was to obtain synthetic calcium phosphate bone graft substitute. X-ray diffraction was employed to investigate the formation of the beta-tricalcium phosphate (β-TCP) phase. We evaluated the effects of bone marrow on the osteoconductivity and mechanical properties of synthetic bone graft (SG). SG cylinders loaded with bone marrow (SGBM) and SG alone were implanted into rabbits femoral condyle bone defects. Histological examinations revealed the resorption of the SG, trabecular bone with osteoblasts and osteoid substance around the implants, and colonization inside the porous β-TCP by newly formed bone. Histomorphometry conducted after three months revealed the osteoid surface to be higher in SGBM than SG (p < 0.05). The compressive strengths of SG and SGBM were significantly higher than the anatomic control at all time periods. The elastic modulus of SBG and SGBM became weaker after implantation. The present results indicate that β-TCP is a good matrix for bone marrow, which contributes osteoinductive properties in an orthotopic. The composite biomaterial may be useful in reconstructive bone surgery.
Silver nanoparticle-based spectrophotometric method for quantification of nile blue A in river water
S.S. Mortazavi,R. Sahraei,A. Farmany 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4
A novel and sensitive spectrophotometric method is developed for the determination of nanomolar level of nile blue A in water samples based on its catalytic effect of silver nanoparticles on the oxidation of nile blue A by hexacyanoferrate (III) in acetate-acetic acid medium and at 25 ℃. The absorbance is measured at 595.5 nm with the fixed-time method. The optimization of the operating conditions regarding concentration of the reagents, temperature and interferences is also investigated. The calibration curve is linear over the concentration range between 85 and 2000 nM of nile blue A with good precision and accuracy. The detection limit of the method is down to 54. The relative standard deviation for a standard solution of 100.0 nM of nile blue A is 1.63% (n = 10). The proposed method provides a highly sensitive, selective and relatively rapid assay for nile blue A at nanomolar level without any pre-concentration and separation step. The method was applied to the determination of nile blue A in river water samples.
S.S. Mortazavi,A. Farmany 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.6
Catalytic-oxidation of Janus green was made in the presence of AgNPs. The reaction was monitoredspectrophotometrically at 610 nm. The system was optimized for the trace analysis of iodate. Themethod is featured with good accuracy and reproducibility for iodate monitoring in real samples withoutany pre-concentration and separation step.
A computational and experimental investigation of the mechanical properties of single ZnTe nanowires
Davami, Keivan,Mortazavi, Bohayra,Ghassemi, Hessam M.,Yassar, Reza S.,Lee, Jeong-Soo,Ré,mond, Yves,Meyyappan, M. The Royal Society of Chemistry 2012 Nanoscale Vol.4 No.3
<P>One-dimensional nanostructures such as ZnTe, CdTe, Bi(2)Te(3) and others have attracted much attention in recent years for their potential in thermoelectric devices among other applications. A better understanding of their mechanical properties is important for the design of devices. A combined experimental and computational approach has been used here to investigate the size effects on the Young's modulus of ZnTe nanowires (NWs). The mechanical properties of individual ZnTe nanowires in a wide diameter range (50-230 nm) were experimentally measured inside a high resolution transmission electron microscope using an atomic force microscope probe with the ability to record in situ continuous force-displacement curves. The in situ observations showed that ZnTe NWs are flexible nanostructures with the ability to withstand relatively high buckling forces without becoming fractured. The Young's modulus is found to be independent of nanowire diameter in the investigated range, in contrast to reported results for ZnO NWs and carbon nanotubes where the modulus increases with a decrease in diameter. Molecular dynamics simulations performed for nanowires with diameters less than 20 nm show limited size dependence for diameters smaller than 5 nm. The surface atoms present lower Young's modulus according to the simulations and the limited size dependency of the cylindrical ZnTe NWs is attributed to the short range covalent interactions.</P>
M.S. Aghakhani,A.A. Khodadadi,Sh. Najafi,Y. Mortazavi 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
Catalytic composites of Y-zeolite-amorphous silica–alumina (ASA) were prepared by four different methods to enhance pre-cracking and cracking of triisopropylbenzene (TIPB). TIPB cracking on composite catalysts were compared with a conventionally prepared catalyst. The samples were characterized by FESEM, XRD, N2-adsorption and NH3-TPD. The catalysts performance was evaluated by triisopropylbenzene cracking at 350˚ C in a fixed bed reactor. The coke content of the catalysts was measured by TPO. Compared to the conventional catalyst, significantly deeper cracking to benzene of about 117% higher, up to 62% lower amount of coke, and lower deactivation rate are observed for the composite catalysts.
R. Khatiri,A. Reyhani,S.Z. Mortazavi,M. Hossainalipour 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5
In this study, the synthesis of four layer structures coated on magnetite nanoparticles such that Fe3O4/SiO2/APTES/PEG/BSA was investigated. Magnetite nanoparticles were synthesized by co-precipitating Fe2+ and Fe3+ in an ammonia solution with the average size of 25 nm. To fabricate Fe3O4/SiO2 core–shells,the magnetite nanoparticles coated by silica with Stober method. The fabricated nanoparticles were treated by 3-aminopropyl-triethoxysilane to achieve Fe3O4/SiO2/APTES nanostructures. Moreover, the nanoparticles were also attached to reactive polyethylene glycol chains. Eventually, the nanoparticles activated with bovine serum albumin for bio-application. X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, UV–vis spectroscopy and vibrating sample magnetometer were used to support the characterization.
V. Izadkhah,A. Farmany,S.S. Mortazavi 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1
In the present study, a novel Schiff base modified multiwalled carbon nanotube paste sensor wasdeveloped for the determination of trace amounts of copper in environmental samples. It is based on theencapsulation of the C24H30N6 Schiff base onto multiwalled carbon nanotube paste electrode. Theoperating conditions regarding supporting electrolytes, deposition time and applied potential on thesensitivity of electrode were established and optimized in detail. The working curve was linear in theconcentration range of 0.09–340 mg L 1. The relative standard deviation for 3 replicate determination ofthe 30 mg L 1 Cu(II) was 1.47%. The detection limit and quantification limit were 0.01 and 0.06 mg L 1,respectively. The sensor was successfully applied to the determination of copper in the river and citywater.