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991.
Mohammad Tavakkoli Vahid Taghikhani Mahmoud Reza Pishvaie Mohsen Masihi Sai R. Panuganti 《Journal of Dispersion Science and Technology》2014,35(8):1155-1162
The presence of asphaltene means additional difficulties related to transport and processing due to the increased crude oil viscosity caused by the asphaltene. For a better knowledge of the flow properties of asphaltene containing crude oils, it is necessary to understand how asphaltene affects the rheological properties. The aim of this article is to provide information on such rheological properties of oil–asphaltene slurry systems. The results of rheological experiments show that the non-Newtonian flow curves can be approximated by the Bingham plastic model to determine the apparent viscosity and the yield stress as a function of asphaltene concentration and temperature. An explanation is also provided for the observed behavior. 相似文献
992.
In(OTf)3 plays the role of a Lewis acid catalyst in the Pechmann condensation of phenols with β-ketoesters under solvent-free conditions to give coumarin derivatives. This novel and inexpensive method has advantages such as short reaction time, excellent product yields, and avoids the use of organic solvents in agreement with green chemistry principles. Catalyst loadings can be as low as 1 mol% to give high yields of the corresponding coumarins at 80 °C. The catalyst can be recovered after the reaction, and reused with only a slight decrease in the yield. 相似文献
993.
The effect of carbon black(CB) and graphite(G) powders on the macroscopic and nano-scale free volume properties of silicone rubber based on poly(di-methylsiloxane)(PDMS) was studied through thermal and cyclic mechanical measurements, as well as with positron annihilation lifetime spectroscopy(PALS). The melting temperature of the composites(Tm) and the endothermic enthalpy of melting(?Hm) were estimated by differential scanning calorimetry(DSC). Tm and the degree of crystallinity(χc) of PDMS composites were found to decrease with increasing the CB content. This can be explained due to the increase in physical cross-linking which results in a decrease in the crystallite thickness. Besides, χc was found to be dependent on the filler type. Cyclic stress-strain behavior of PDMS loaded with different contents of filler has been studied. Mullins ratio(RM) was found to be dependent on the filler type and content. It was found that, RM increases with increasing the filler content due to the increase in physical cross-linking which results in a decrease in the size of free volume, as observed through a decrease of the o-Ps lifetime τ3 measured by PALS. Moreover, the hysteresis in PDMS-CB composites was more pronounced than in PDMS-G composites. Furthermore, a correlation was established between the free volume Vf and the mechanical properties of PDMS composites containing different fillers. A negative correlation was observed between Vf and RM. 相似文献
994.
Mohsen Ameri Alireza Asghari Ali Amoozadeh Hassan Daneshinejad Davood Nematollahi 《中国化学快报》2014,25(5):797-801
Electrochemical oxidation of hydroquinone(1a) has been studied in the presence of 6-methyl-2-thiouracil(3a) and 6-propyl-2-thiouracil(3b) as nucleophiles in a DMF/buffer mixture,using cyclic voltammetry and controlled-potential coulometry.The results indicated that the p-quinone(2a) derived from 1a participates in a 1 4-Michael addition reaction with the thiouracil derivatives(3a–b) to form the corresponding hydroquinonethioether derivatives(6a–6b).The electrosynthesis of these compounds(6a–b) has been successfully performed on carbon rod electrodes in an undivided cell in good yield and purity. 相似文献
995.
A sensitive electrochemical sensor for the determination of cysteamine(CA) was developed using a modified multiwall carbon nanotube paste electrode(MWCNTPE) with isoproterenol(ISPT) as a mediator.This modified electrode showed very high electrocatalytic activity for the anodic oxidation of CA.Under the optimized conditions,the electrocatalytic peak current showed a linear relationship with CA concentration in the range of 0.3–450.0 mmol/L with a detection limit of 0.09 mmol/L CA.The modified electrode was used for the determination of CA in real samples such as urine and drug samples. 相似文献
996.
Mohsen Ameri Alireza Asghari Ali Amoozadeh Mohammad Bakherad Davood Nematollahi 《中国化学快报》2014,25(12):1607-1610
Electrochemical oxidation of 4-methyl catechol(1a) is investigated in the presence of 1,3-indandione(3)as nucleophile in phosphate buffer solution(0.2 mol/L,pH 6) mixed with ethanol as organic green solvent(50/50) using cyclic voltammetry and controlled-potential coulometry.The results indicated thatquinones derived from electro-oxidation of 1a,participated in a 1,4-Michael addition reaction with1,3-indandione(3) under ECCE mechanism.In this direction,a new bis-quinone was synthesized in high yield and good purity using a facile and convenient electrochemical pathway by carbon anode electrodes in an undivided cell. 相似文献
997.
Seyed Mohsen Sadeghzadeh Mohammad Ali Nasseri 《Journal of the Iranian Chemical Society》2014,11(4):1197-1205
FeNi3\SiO2\HPG\PbS magnetic nanoparticles (MNPs) catalyst was readily prepared from inexpensive starting materials in aqueous media which catalyzed the synthesis 2-amino-4H-chromene via intermittent microwave irradiation. X-ray diffraction, transmission electron micrographs, and scanning electron micrographs were employed to characterize the properties of the synthesized FeNi3\SiO2\HPG\PbS MNPs. High catalytic activity and ease of recovery from the reaction mixture using external magnet and several reuse times without significant losses in performance are additional eco-friendly attributes of this catalytic system. 相似文献
998.
Fatemeh Shojaei Naemeh Tavakolinia Adeleh Divsalar Thomas Haertlé Ali Akbar Saboury Mohsen Nemat-Gorgani Maria Pia Abbracchio 《Journal of the Iranian Chemical Society》2014,11(6):1503-1512
Protein aggregation is commonly associated with a large number of neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and other types of pathological conditions. Misfolding and aggregation of a number of peptides and proteins have been found to occur under these conditions. In the present review, some mechanistic features of the events related to the type of structure–function relationships which may define the outcome of the abnormal conditions are discussed. The immunological responses to the aggregates and possible therapeutic strategies for prevention or control of the diseases are also reviewed. Protein aggregation and its effect on human body have become an important issue over the last two decades. Many diseases in human are related to aggregation and misfolding of different kinds of proteins; therefore, diagnosis of causes of the aggregation and their mechanisms which provoke it are important. This review describes the relations between structures and functions of already aggregated proteins, as well as proteins, which only enter initial stages of aggregation. The consequences of aggregations, which provoke many kinds of neurodegenerative disorders, are explained in details and some factors that may influence their severity are described. In addition, the immunologic responses to these aggregates are discussed. Suggestions of plausible therapies of preventing or slowing down the protein condensation diseases are presented. 相似文献
999.
Tannaz Tavari Saber Meamardoost Naserodin Sepehry Pooria Akbarzadeh Mostafa Nazari Nicole N Hashemi Mohsen Nazari 《Electrophoresis》2023,44(3-4):450-461
To date, a comprehensive systematic optimization framework, capable of accurately predicting an efficient electrode geometry, is not available. Here, different geometries, including 3D step electrodes, have been designed in order to fabricate AC electroosmosis micropumps. It is essential to optimize both geometrical parameters of electrode, such as width and height of steps on each base electrode and their location in one pair, the size of each base electrode (symmetric or asymmetric), the gap of electrode pairs, and nongeometrical parameters such as fluid flow in a channel and electrical characteristics (e.g., frequency and voltage). The governing equations comprising of electric domain and fluid domain have been coupled using finite element method. The developed model was employed to investigate the effect of electrode geometric parameters on electroosmotic slip velocity and its subsequent effect on pressure and flow rate. Numerical simulation indicates that the optimal performance can be achieved using a design with varying step height and displacement, at a given voltage (2.5 V) and frequency (1 kHz). Finally, in order to validate the numerical simulation, the optimal microchip was fabricated using a combination of photolithography, electroplating, and a polydimethylsiloxane microchannel. Our results indicate that our micropump is capable of generating a pressure, velocity, and flow rate of 74.2 Pa, 1.76 mm/s, and 14.8 µl/min, respectively. This result reveals that our proposed geometry outperforms the state-of-the-art micropumps previously reported in the literature by improving the fluid velocity by 32%, with 80% less electrodes per unit length, and whereas the channel length is ∼80% shorter. 相似文献
1000.
Mohsen M Zareh 《Analytical sciences》2008,24(7):889-894
TFPB was introduced as a charged ionophore for atropine selective electrodes. Typical Nernstian responses were found (57.78, 58.95 and 58.41 mV/decade) for PVC-membrane electrodes incorporating NPOE, DOS, and DDP as plasticizers. They exhibited practical linear ranges of 9.1 x 10(-3) - 10(-6), 9.1 x 10(-3) - 10(-6) and 9.1 x 10(-3) - 10(-7) M, respectively. It works in the sub-micro scale of atropine concentrations. The optimum pH-range was 3.18 - 8.97. The selectivity coefficient values were estimated for different organic and inorganic cations. They were interpreted by using the "Relative Selectivity Concept", which was introduced for the first time. The new concept was applied for comparing the selectivity properties of previously reported electrodes. The effect of the presence of ephedrine, caffeine, glucose, Na(+), Ca(2+), and Mg(2+) on the calibration graphs of the electrodes was studied. 相似文献