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Search Results: 1 - 10 of 72 matches for " Meisam Alitabarimansor "
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Hydrolysis of Virgin Coconut Oil Using Immobilized Lipase in a Batch Reactor
Lee Suan Chua,Meisam Alitabarimansor,Chew Tin Lee,Ramli Mat
Enzyme Research , 2012, DOI: 10.1155/2012/542589
Abstract: Hydrolysis of virgin coconut oil (VCO) had been carried out by using an immobilised lipase from Mucor miehei (Lipozyme) in a water-jacketed batch reactor. The kinetic of the hydrolysis was investigated by varying the parameters such as VCO concentration, enzyme loading, water content, and reaction temperature. It was found that VCO exhibited substrate inhibition at the concentration more than 40% (v/v). Lipozyme also achieved the highest production of free fatty acids, 4.56?mM at 1% (w/v) of enzyme loading. The optimum water content for VCO hydrolysis was 7% (v/v). A relatively high content of water was required because water was one of the reactants in the hydrolysis. The progress curve and the temperature profile of the enzymatic hydrolysis also showed that Lipozyme could be used for free fatty acid production at the temperature up to 50°C. However, the highest initial reaction rate and the highest yield of free fatty acid production were at 45 and 40°C, respectively. A 100 hours of initial reaction time has to be compensated in order to obtain the highest yield of free fatty acid production at 40°C. 1. Introduction Coconut oil, which is derived from the seeds of coconut palm, Cocos nucifera, is traditionally processed from the meat of the fruit, called copra. Copra is the dried kernel that produced by smoke drying, sun drying, or a combination of both methods. Therefore, it is usually colorless to pale brownish yellow. Recently, the most welcomed product from coconut is virgin coconut oil (VCO), particularly from the tropical countries. The concept of producing VCO is actually triggered by the well-known virgin olive oil that produced from Mediterranean Basin. The high demand for the virgin oils is definitely due to the preservation of oil composition, including the minor components such as provitamin A, vitamin E, phytosterols, and polyphenols, without aflatoxin contamination and oxidative rancidity from drastic processing and handling approach. These minor components are believed to have the nutritional benefits. By definition, VCO is defined as the oil obtained from the fresh, mature kernel of coconuts by mechanical or natural means without the use of heat, chemical refining, bleaching, and odorizing which does not lead to the alteration of the natural content of the oil [1]. It should also have the moisture content less than 0.1%. Because of the beneficial effects on human health [2, 3] and high saturation degree [1] as well as high oxidative stability of VCO [4], the oil is the great source of oil material for the production of value-added
Elastic free-energy of wormlike micellar chains: theory and suggested experiments
Meisam Asgari
Physics , 2015,
Abstract: The extensive application of surfactants motivates comprehensive and predictive theoretical studies that improve our understanding of the behaviour of these complex systems. In this study, an expression for the elastic free-energy density of a wormlike micellar chain is derived taking into account interactions between its constituent molecules. The resulting expression incorporates the sum of a quadratic term in the curvature and a quadratic term in the torsion of the centerline of wormlike micelle and thus resembles free-energy density functions for polymer chains and DNA available in the literature. The derived model is applied on a wormlike micelle in the shape of a circular arc, open or closed. A detailed application of the derived model on wormlike micelles of toroidal shape, along with employing necessary statistical-thermodynamical concepts of self-assembly, is performed, and the results are found to be consistent with the ones available in the literature. Steps towards obtaining the material parameters through experiments are suggested and discussed.
The Effects of Annealing Process on Dielectric and Piezoelectric Properties of BMT-Base Lead-Free Ceramics  [PDF]
Mahdi Ghasemifard, Meisam Daneshvar, Misagh Ghamari
World Journal of Nano Science and Engineering (WJNSE) , 2013, DOI: 10.4236/wjnse.2013.33014
Abstract:
By using nitric acid as the fuel, the lead-free ceramic of Ba(Ti1-x,Mgx)O3 (x = 0.31) was prepared by auto combustion method (ACM). To make a comparison, this ceramic was also prepared using mixed oxide method (MOM). By X-ray diffraction, the phase structures of two samples were studied, and the results showed that rising temperatures would reduce unwanted phases. The piezoelectric and electrical properties as a function of calcination and sintering temperatures were investigated. The results showed that the outstanding electrical properties were obtained for nanoceramic with this composition. The SEM image of the grain size was estimated around 2 micrometers, and the grain size increased with the increasing of sintering temperature for two samples. The curie temperature of the BMT-ACM was 126°C and it’s significantly larger than the curie temperature of BMT-MOM which was 118°C. The results of electrical properties emphasized that the synthesis optimum temperature for two samples was about 1200°C and it was the best temperature that led to improved properties such as dielectric constant, polarization and piezoelectric coefficients.
Virtual Reality Driving Simulation for Measuring Driver Behavior and Characteristics  [PDF]
Seyyed Meisam Taheri, Kojiro Matsushita, Minoru Sasaki
Journal of Transportation Technologies (JTTs) , 2017, DOI: 10.4236/jtts.2017.72009
Abstract: This article provides new insights regarding driver behavior, techniques and adaptability. This study has been done because: 1) driving a vehicle is critical and one of the most common daily tasks; 2) simulators are used for the purpose of training and researching driver behavior and characteristics; 3) the article addresses driver experience by involving new virtual reality technologies. A simulator has been used to assist novice drivers to learn how to drive in a very safe environment, and researching and collecting data for researchers has become easier due to this secure and user-friendly environment. The theoretical framework of this driving simulation has been designed by using the Unity3D game engine (5.4.f3 version) and was programmed with the C# programming language. To make the driving environment more realistic we, in addition, utilized the HTC Vive Virtual reality headset which is powered by Steamvr. We used Unity Game Engine to design our scenarios and maps because by doing this we are able to be more flexible with designing. In this study, we asked 10 people ranging from ages 19 - 37 to participate in this experiment. Four Japanese divers and six non-Japanese drivers engaged in this study, some of which do not have a driver’s license in Japan. A few Japanese drivers have a license and car, while others have a license but no car. In order to analyze the results of this experiment we are used MatlabR2016b to analyze the gathered data. The result of this research indicates that individual’s behavior and characteristics such as controlling the speed, remaining calm and relaxed when driving, driving at appropriate speeds depending on changes in road structures and etc. can affect their driving performance.
Development of a Driving Simulator with Analyzing Driver’s Characteristics Based on a Virtual Reality Head Mounted Display  [PDF]
Seyyed Meisam Taheri, Kojiro Matsushita, Minoru Sasaki
Journal of Transportation Technologies (JTTs) , 2017, DOI: 10.4236/jtts.2017.73023
Abstract: Driving a vehicle is one of the most common daily yet hazardous tasks. One of the great interests in recent research is to characterize a driver’s behaviors through the use of a driving simulation. Virtual reality technology is now a promising alternative to the conventional driving simulations since it provides a more simple, secure and user-friendly environment for data collection. The driving simulator was used to assist novice drivers in learning how to drive in a very calm environment since the driving is not taking place on an actual road. This paper provides new insights regarding a driver’s behavior, techniques and adaptability within a driving simulation using virtual reality technology. The theoretical framework of this driving simulation has been designed using the Unity3D game engine (5.4.0f3 version) and programmed by the C# programming language. To make the driving simulation environment more realistic, the HTC Vive Virtual reality headset, powered by Steamvr, was used. 10 volunteers ranging from ages 19 - 37 participated in the virtual reality driving experiment. Matlab R2016b was used to analyze the data obtained from experiment. This research results are crucial for training drivers and obtaining insight on a driver’s behavior and characteristics. We have gathered diverse results for 10 drivers with different characteristics to be discussed in this study. Driving simulations are not easy to use for some users due to motion sickness, difficulties in adopting to a virtual environment. Furthermore, results of this study clearly show the performance of drivers is closely associated with individual’s behavior and adaptability to the driving simulator. Based on our findings, it can be said that with a VR-HMD (Virtual Reality-Head Mounted Display) Driving Simulator enables us to evaluate a driver’s “performance error”, “recognition errors” and “decision error”. All of which will allow researchers and further studies to potentially establish a method to increase driver safety or alleviate “driving errors”.
Biodegradable Orthopedic Magnesium-Calcium (MgCa) Alloys, Processing, and Corrosion Performance
Meisam Salahshoor,Yuebin Guo
Materials , 2012, DOI: 10.3390/ma5010135
Abstract: Magnesium-Calcium (Mg-Ca) alloy has received considerable attention as an emerging biodegradable implant material in orthopedic fixation applications. The biodegradable Mg-Ca alloys avoid stress shielding and secondary surgery inherent with permanent metallic implant materials. They also provide sufficient mechanical strength in load carrying applications as opposed to biopolymers. However, the key issue facing a biodegradable Mg-Ca implant is the fast corrosion in the human body environment. The ability to adjust degradation rate of Mg-Ca alloys is critical for the successful development of biodegradable orthopedic implants. This paper focuses on the functions and requirements of bone implants and critical issues of current implant biomaterials. Microstructures and mechanical properties of Mg-Ca alloys, and the unique properties of novel magnesium-calcium implant materials have been reviewed. Various manufacturing techniques to process Mg-Ca based alloys have been analyzed regarding their impacts on implant performance. Corrosion performance of Mg-Ca alloys processed by different manufacturing techniques was compared. In addition, the societal and economical impacts of developing biodegradable orthopedic implants have been emphasized.
PREPARATION OF NEW OPTICALLY ACTIVE AND THERMALLY STABLE POLY(AMIDE-IMIDE) CONTAINING BICYCLO SEGMENT AND ETHER GROUP IN THE MAIN CHAIN BY DIRECT POLYCONDENSATION IN TWO DIFFERENT MEDIA
FAGHIHI,KHALIL; SHABANIAN,MEISAM;
Journal of the Chilean Chemical Society , 2010, DOI: 10.4067/S0717-97072010000400018
Abstract: a new series of optically active and thermally stable poly(amide-imide)s (pais) with good inherent viscosities based on bicyclo diacids and etheric diamine in the main chain were synthesized from the direct polycondensation reaction of aw'-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-l-amino acids 3a-g with 1,2-bis[4-aminophenoxy]ethane 7 by direct polycondensatios with two different media such as direct polycondensation in a medium consisting of n-methyl-2-pyrrolidone (nmp)/triphenyl phosphite (tpp)/calcium chloride (cacl2)/pyridine (py) and direct polycondensation in a tosyl chloride (tscl)/pyridine (py)/n,n-dimethylformamide (dmf) system. also 3a-g were synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride 1 with two equimolars of various amino acids such as l-alanine 2a, l-valine 2b, l-leucine 2c, l-isoleucine 2d, l-phenylalanine 2e, l-2-aminobutyric acid 2f and l-histidine 2g in an acetic acid solution. the polymerization reactions produced a series of thermally stable and optically active organosoluble pais. the resulting polymers were fully characterized by means of ft-ir and 1h-nmr spectroscopy, elemental analyses, inherent viscosity, specific rotation, solubility tests and differential scanning calorimeter (dsc). also thermal properties of the pais 8a-g were investigated using thermal gravimetric analysis (tga) and derivative of thermaogravimetric (dtg) analysis.
THERMAL AND OPTICAL PROPERTIES OF SILVER-POLYIMIDE NANOCOMPOSITE BASED ON DIPHENYL SULFONE MOIETIES IN THE MAIN CHAIN
FAGHIHI,KHALIL; SHABANIAN,MEISAM;
Journal of the Chilean Chemical Society , 2011, DOI: 10.4067/S0717-97072011000200009
Abstract: a new polyimide-silver nanocomposite containing diphenyl sulfone moiety in the main chain was synthesized using a convenient ultraviolet irradiation technique.agno3 was used as a source of the silver nanoparticles. polyimide 3, as a polymer source , was synthesized by the polycondensation reaction of 4,4'-diamino diphenyl sulfone 1 with pyromellitic anhydride 2 in the presence of iso-quinoline as base and m-cresol as solvent. the resulting composite film 3a was characterized by ftir spectroscopy, uv-vis analysis, x-ray diffraction (xrd), transmission electron microscopy (tem), thermogravimetry analysis (tga) and differential scanning calorimetry (dsc). the x-ray diffraction analysis reveals that silver nanoparticles are present in polyimide matrix. this data is in good agreement with the result obtained from tem and shows the silver nanoparticles homogeneously dispersed in the polyimide matrix. the uv-vis spectrum shows a single peak at 425 nm, arising from the surface plasmon absorption of the silver nanoparticles.
Synthesis and characterization of new optically active poly(amide-imide)s based on N-trimellitimido-L-amino acid and trimethylene units
Khalil Faghihi, Meisam Shabanian
Bulletin of the Chemical Society of Ethiopia , 2011,
Abstract: Six new optically active poly(amide-imide)s (8a-f) were synthesized through the direct polycondensation reaction of 1,3-bis(4-aminophenoxy) propane (4) with six different derivatives of N-trimellitimido-L-amino acid (7a-f) in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride and pyridine. The polycondensation reaction produced a series of novel poly(amide-imide)s (8a-f) containing trimethylene moiety in the main chain in high yield with inherent viscosities between 0.45 and 0.80 dL/g. The resulting polymers were fully characterized by means of FTIR spectroscopy, elemental analyses, inherent viscosity, and solubility tests. Thermal properties of these polymers were investigated by thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG). All of the polymers were readily soluble in a variety of organic solvents such as N,N'-dimethyl formamide (DMF), N,N'-dimethyl acetamide (DMAc), dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP) at room temperature. They had 10% weight loss at a temperature above 360 °C and left 42.0–55.6% residue even at 600 °C in nitrogen. KEY WORDS: High performance polymers, Poly(amide-imide)s, Direct polycondensation, Trimethylene moiety Bull. Chem. Soc. Ethiop. 2011, 25(1), 97-102.
EBG Frequency Response Tuning Using an Adjustable Air-Gap
Mehdi Veysi;Meisam Shafaee
PIER Letters , 2010, DOI: 10.2528/PIERL10101002
Abstract: A new adjustable Electromagnetic Band-Gap (EBG) structure whose frequency response is controllable by adjusting spacer height is proposed. The finite difference time domain method is adopted for the simulations. Results show that the desired frequency response can be selected by adjusting the spacer height. The effects of the air-gap on the polarization dependent and conventional EBG structures have been investigated both theoretically and numerically. The agreement between the theoretical calculations and numerical results is reasonably good.
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