Search for: growth-kinetics
Total 28 records
Electrochemical behavior of nanostructured fe-pd alloy during electrodeposition on different substrates, Article Journal of Electrochemical Science and Technology ; Volume 9, Issue 3 , 2018 , Pages 202-211 ; 20938551 (ISSN) ; Haghshenas, D. F ; Ghorbani, M ; Dolati, A ; Sharif University of Technology
Korean Electrochemical Society 2018
In this work, Fe-Pd alloy films have been electrodeposited on different substrates using an electrolyte containing [Pd(NH3)4]2+ (0.02 M) and [Fe-Citrate]2+ (0.2 M). The influences of substrate and overpotential on chemical composition, nucleation and growth kinetics as well as the electrodeposited films morphology have been investigated using energy dis-persive X-ray spectroscopy (EDS), current-time transients, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) patterns. In all substrates – brass, copper and sputtered fluorine doped tin oxide on glass (FTO/glass) – Fe content of the electrodeposited alloys increases by increasing the overpotential....
Application of power law logistic model to growth kinetics of bacillus licheniformis MS3 on a water- insoluble substrate, Article Chemical Engineering Communications ; Volume 201, Issue 11 , 06 June 2014 , Pages 1514-1525 ; Maghsoudi, E ; Roostaazad, R ; Sharif University of Technology
The power law logistic model was utilized to investigate the growth of a hydrocarbon assimilating bacterium on a water-insoluble substrate. To achieve this end, population dynamics of Bacillus licheniformis MS3 in a medium containing n-decane as the sole carbon source was monitored for 30 h. Different initial biosurfactant concentrations and shaking rates were employed to examine the role of mass transfer in the cell growth and the consequent hydrocarbon biodegradation. The amount of n-decane degraded in the system was detected by gas chromatography at the end of the incubation period. The results revealed that when mass transfer limitations were lessened through addition of an initial...
Article CHISA 2006 - 17th International Congress of Chemical and Process Engineering, Prague, 27 August 2006 through 31 August 2006 ; 2006 ; 8086059456 (ISBN); 9788086059457 (ISBN) ; Vossoughi, M ; Soltanieh, M ; Rizi, Z. T ; Sharif University of Technology
Most sulfide oxidizing bioreactors are based on pure cultures or artificial mixes of microorganisms with strict requirements for growth, which make the system unstable and do not guarantee their long term performance. The ultimate goal of this study is to develop a natural mix of chemotrophic bacteria that may be applied anaerobically for the treatment of sour gas. Activated sludge from local municipal wastewater treatment plant that was maintained in endogenous anaerobic conditions for one year was used in this study. Total suspended solids (TSS) and volatile suspended solids (VSS) of the sludge was 22 gl-1 and 14.3 gl-1, respectively. A glass culture vessel had a volume of 0.65 L was used...
Article Journal of Alloys and Compounds ; Volume 770 , 2019 , Pages 784-791 ; 09258388 (ISSN) ; Nemati, A ; Maleki Shahraki, M ; Sharif University of Technology
Elsevier Ltd 2019
Up to now, attempts for developing coarse-grained SnO2-based varistors which exhibit high nonlinearity property at lower voltage have become a challenge without any prominent result because of its unknown grain growth mechanism. In this study, the effect of CuO addition to SnO2-based varistors as a grain growth enhancer additive on microstructural development, grain growth kinetics, and electrical properties was investigated. The characterization of grain growth kinetics showed that CuO addition encouraged grain growth and enhanced the grains size as it could be seen in the activation energy which decreased from 594 kJ/mol to 364 kJ/mol. In the samples with a low amount of CuO, the solute...
M.Sc. Thesis Sharif University of Technology ; Roosta Azad, Reza ; Yaghmaei, Soheyla
Evidently, environment contamination by water insoluble chemicals present at the industrial wastes could bring about catastrophic consequences to the biosphere. Biological based cleaning technologies are commonly considered as a practical remedy to remove these contaminations. In fact, these techniques are founded on the ability of certain microorganisms to degrade the contaminants. It is crystal clear that the availability of contaminants to the microorganisms is an essential parameter determining the final efficiency of the biodegradation process. In practice, the limited solubility of the contaminants in the aqueous phase leads to mass transfer constraints which consequently, decrease the...
Microstructure, Properties and Kinetic Characterization in SnO2-Based Varistor with Addition of CuO Nano Particle, M.Sc. Thesis Sharif University of Technology ; Nemati, Ali ; Seyyed Reyhani, Morteza
The aim of this study is to investigate the effect of Copper oxide on the microstructure, properties, and grain growth kinetic in Tin oxide- Based varistors. Copper oxide was mixed in Tin oxide with different concentration, including 0, 0.1, 0.25, 0.5, and 1 mol% and the samples were sintered at 1250, 1300, and 1350 oC. Then, phase and microstructural characterization was investigated and consequently, electrical properties were evaluated. According to results, Copper Oxide with forming the liquid phase through the sintering process, accelerated grain growth. It was found that, by increasing concentration of CuO, mean grain size was increased from 2.6 µm in 1250 oC and 5 hours to 17.1 µm...
Colloidal Synthesis of CdSe Nanoparticles and the Influence of Processing Parameters on Growth kinetics, M.Sc. Thesis Sharif University of Technology ; Asgari, Sirous
Over the past two decades, several studies have been investigated on synthesis and properties of semi-conductor quantum dots because of their applications in sensors, LEDs, detectors, solar cells, etc. One of challenging issues in synthesizing these nano-particles is their size distribution. In this study, Cadmium Selenide was synthesized by the method of colloidal synthesis. X-ray diffraction showed that the crystalline nano-particles have wurtzite structure. For obtaining a uniform size distribution, effect of various parameters such as molar ratio of components and reaction temperature on the growth kinetics of these particles, were studied. Results showed that molar ratio of Selenium to...
Article Journal of Electroanalytical Chemistry ; Volume 577, Issue 1 , 2005 , Pages 1-8 ; 15726657 (ISSN) ; Ghorbani, M ; Ahmadi, M. R ; Sharif University of Technology
Cyclic voltammetry, j-t transients and transient time measurements have been used to characterize the Au-Ni alloy deposition and to obtain the nucleation and growth mechanism. The electrodeposition of gold, nickel and gold-nickel alloys was studied in cyanide-citrate electrolytes. The analysis of the voltammograms and j-t transients clearly shows that deposition of the Au and hence, of Au-Ni alloys, is affected by adsorbed cyanide ligands mainly at low overpotentials and a direct reduction occurs at high overpotentials. In this case, the Au deposition is kinetically favored, while the Ni deposition is controlled by the cyanide-citrate adsorbed adlayer. In an alloy electrolyte, the Au and Ni...
Effect of Bioglass Particle Size and Titania Morphology on the Bioactivity and Kinetics of Tissue Growth in Three-Dimensional Poly(ɛ-Caprolactone) Scaffolds with Controlled Pore Structure Produced by 3D-Printing Process, Ph.D. Dissertation Sharif University of Technology ; Bagheri, Reza ; Vossoughi, Manouchehr ; Simchi, Abdolreza
Polycaprolactone (PCL) scaffolds and its composites containing bioactive glass particles (45S5) and TiO2 nanostructures with pre-defined and controlled external and internal architecture were prepared via an indirect three-dimensional (3D) printing process. The scaffolds had an interconnected structure with macro- (400-500 μm) and micro- (~25 μm) pores. Bioactivity, mechanical behavior and kinetics of tissue growth in 3D scaffolds were studied. The size effect of biogactive glass particles (6 μm, 250 nm, <100 nm) and morphology of titania nanostructures (spherical, tube, leaf-like, and flower-like particles) were elaborated. The biogactive glass particles with different sizes were prepared...
Application of Bioleaching Technology in Extraction of Metals from Spent Catalysts of Petroleum Refinery, Ph.D. Dissertation Sharif University of Technology ; Yaghmaei, Soheyla ; Mousavi, Mohammad
In this project, bioleaching has been investigated as a solution for detoxification and metal recovery of spent hydrocracking catalysts of Tehran petroleum refinery which is listed as a hazardous waste. In this project four stages has been accomplished as follows: 1- Adaptation of Penicillium simplicissimum and Aspergillus niger with different heavy metals present in a spent hydrocracking catalyst, individually and with mixture of metals as well as adaptation by spent catalyst which the cumulative action of multi-metals enhanced the toxic effect; 2- The one-step, two-step, and spent medium bioleaching of the spent catalyst by the adapted fungi in batch cultures were investigated and...
Study of Antibacterial Performance of Metal Oxide Nanostructures and their Effect on Bacterial Growth Kinetics, M.Sc. Thesis Sharif University of Technology ; Naseri, Naimeh ; Zaker Moshfegh, Alireza
Fighting contagious microbial diseases is considered a serious health issue, which has attracted much attention in worldwide. Thus, development of new materials based on nanostructures as a new generation of antibiotics to address this challenge has been of interest to researchers in recent years. Nanostructures based on metallic oxide semiconductors such as oxides with light absorption, production of electron-hole pairs in needle like structures cause tearing bacterial membrane and eventually destroy the bacterium. To this end, we designed experiments to study mechanism and physics governing the process of bacterial degradation to determine the best conditions for inhibiting bacteria...
Simulation of competition between two microorganisms in a biofilm reactor based on different growth models, Article Biochemical Engineering Journal ; Volume 23, Issue 1 , 2005 , Pages 63-72 ; 1369703X (ISSN) ; Yaghmaei, S ; Sharif University of Technology
A simple biofilm model based on a model suggested by Soda et al. [S. Soda, E. Heinzle, M. Fujita, Modeling and simulation of competition between two microorganisms for a single inhibitory substrate in a biofilm reactor, Biotechnol. Bioeng. 66 (1999) 258-264] was used to simulate the competition between two microorganisms for space and a single inhibitory substrate in a biofilm reactor. Different growth kinetics were used to describe the growth of two microorganisms A and B which utilize the inhibitory substrate and the effect of biofilm thickness on microorganism concentration in biofilm was discussed. It was assumed that the biofilm has a uniform thickness and is composed of N segments (N =...
Article Separation and Purification Technology ; Volume 80, Issue 3 , August , 2011 , Pages 566-576 ; 13835866 (ISSN) ; Mousavi, S. M ; Yaghmaei, S ; Sharif University of Technology
Statistically based experimental designs were applied to screen and optimize the bioleaching of spent hydrocracking catalyst by Penicillium simplicissimum. Eleven factors were examined for their significance on bioleaching using a Plackett-Burman factorial design. Four significant variables (pulp density, sucrose, NaNO3, and yeast extract concentrations) were selected for the optimization studies. The combined effect of these variables on metal bioleaching was studied using a central composite design (CCD). Second-order polynomials were established to identify the relationship between the recovery percent of the metals and the four significant variables. The optimal values of the variables...
Chromium carbonitride coating produced on DIN 1.2210 steel by thermo-reactive deposition technique: Thermodynamics, kinetics and modeling, Article Surface and Coatings Technology ; Volume 225 , 2013 , Pages 1-10 ; 02578972 (ISSN) ; Nazari, A ; Khoie, S. M. M ; Khalaj, M. J ; Pouraliakbar, H ; Sharif University of Technology
A duplex surface treatment on DIN 1.2210 steel has been developed involving nitriding and followed by chromium thermo-reactive deposition (TRD) techniques. The TRD process was performed in molten salt bath at 550, 625 and 700°C for 1-14h. The process formed a thickness up to 9.5μm of chromium carbonitride coatings on a hardened diffusion zone. Characterization of the coatings by means of scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) indicates that the compact and dense coatings mainly consist of Cr(C,N) and Cr2(C,N) phase. All the growth processes of the chromium carbonitride obtained by TRD technique followed a parabolic kinetics. Activation energy (Q) for the...
Tailoring of morphology and crystal structure of CdSe nanostructures by controlling the ratio of triethylenetetraamine and water in their mixed solution, Article Applied Physics A: Materials Science and Processing ; Volume 107, Issue 2 , May , 2012 , Pages 497-502 ; 09478396 (ISSN) ; Zarghami, V ; Fray, D. J ; Sharif University of Technology
The morphological manipulation, structural characterization, and optical properties of different CdSe nanocrystals were reported. Several different CdSe nanostructures, including nanowires, tetrapod crystals, and nanoparticles were grown by varying the volume ratio of triethylenetetraamine (TETA) and water (WA) in their mixed solution. By manipulating the growth driving force (i.e., the degree of supersaturation) and kinetics of the process (i.e., growth rate), the morphology and crystal structure of CdSe nanocrystals can be tailored. Growth driving force changed their morphology from nanowires to tetrapod structures and from the latter structure to nanoparticles. Moreover, kinetics of the...
Article Advanced Materials Research ; Volume 410 , 2012 , Pages 240-244 ; 10226680 (ISSN) ; 9783037853160 (ISBN) ; Ekrami, A ; Seyed Reihani, S. M ; Mousavi Abarghouie, S. M. R ; Sharif University of Technology
In the present research the aging behavior of Al6061 alloy and Al6061/SiCp composite fabricated by powder metallurgy method was investigated. The solution treatment of the samples were carried out at 527°C for 2, 3and 4 h followed by aging at 180°C for different aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the composite. The peak hardness of the composite took place at shorter times than that of the 6061 alloy for the samples solution treated for 3and 4 h, but took place at longer times for the samples solution treated for 2 h. The optimum solution treating time was about 3 h for both the composite and the 6061 alloy that led to the...
Article Journal of Non-Newtonian Fluid Mechanics ; Volume 223 , 2015 , Pages 240-248 ; 03770257 (ISSN) ; Ramazani, S. A. A ; Ranjbari, R ; Sharif University of Technology
A new rheological model is developed to predict viscous and elastic behavior of concentrated suspensions of short fiber and one dimensional nanoparticles in steady and transient shear flows, simultaneously. The previously presented models cannot predict such rheological behavior with a set of parameters. The reduced strain closure (RSC) model in spite of its ability to successfully reproduce the slow kinetics of orientation growth observed in concentrated short-fiber suspensions is not able to predict both the shear viscosity and the normal stress difference data together, which could be possibly due to the fact that an orientation model with a scalar interaction coefficient cannot predict...
Article Journal of Nanomaterials ; Volume 2010 , August , 2010 ; 16874110 (ISSN) ; Mehranpour, H ; Sasani Ghamsari, M ; Farzalibeik, H ; Sharif University of Technology
Titanium dioxide nanopowders were synthesized by the diffusion controlled sol-gel process (LaMer model) and characterized by DTA-TG, XRD, and SEM. The prepared TiO 2 nanoparticles have uniform size and morphology, and the phase transformation kinetics of obtained material was studied by interpretation of the X-ray diffraction patterns peaks on the base of Avrami equation. The stating point of anatase-rutile phase transformation temperature in the prepared nanoparticles was found between 100 and 200 C. A decreasing trend on the intensity of X-ray peaks of anatase phase was observed up to 600 C when the presence of the rutile phase became predominant. Results indicated that the transition...
Article Materials and Design ; Volume 31, Issue 5 , May , 2010 , Pages 2368-2374 ; 02641275 (ISSN) ; Seyed Reihani, S.M ; Sharif University of Technology
In the present research work the 2024 aluminum alloy was reinforced with SiC particles via powder metallurgy method. The effect of heat treatment conditions on artificial aging kinetics was investigated. The solution treatment of the composite sample and the unreinforced alloy was carried out at 495 °C for 1, 2 and 3 h followed by aging at 191 °C for various aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the alloy. The peak hardness of the composite sample took place at shorter times than that of the unreinforced alloy for the samples solution treated for 2 and 3 h, but took place at longer times for the samples solution treated for 1 h....
Self-limited growth of large-area monolayer graphene films by low pressure chemical vapor deposition for graphene-based field effect transistors, Article Ceramics International ; Volume 43, Issue 17 , 2017 , Pages 15010-15017 ; 02728842 (ISSN) ; Razzaghi, Z ; Ghadiani, B ; Tamizifar, M ; Mohmmadi, M. H ; Simchi, A ; Sharif University of Technology
During the last decade, fabrication of high-quality graphene films by chemical vapor deposition (CVD) for nanoelectronics and optoelectronic applications has attracted increasing attention. However, processing of large-area monolayer and defect-free graphene films is still challenging. In this work, we have studied the effect of processing conditions on the self-limited growth of graphene monolayers on copper foils during low pressure CVD both experimentally and theoretically based on thermokinetics and kinetics of Langmuir adsorption. The effect of copper pre-treatment, growth time, and carbon potential of the atmosphere (indicated by the methane-to-hydrogen gas ratio, r) on the quality of...