Sharif Digital Repository

The electrochemical behavior of antioxidants daidzein (DZ) and 7-hydroxy-4-chromone (7-OH-4-CHM) was investigated. The oxidation of DZ is irreversible, pH-dependent, and occurs in two steps, the first of 4′-OH on the B-ring and the second on the 7-OH on the A-ring. The oxidation of 7-OH-4-CHM occurs on the 7-OH on the A-ring, is irreversible, pH-dependent and proceeds in a single step. The DZ diffusion coefficient was calculated in pH7.0 phosphate buffer to be D DZ=8.1×10 -5cm 2s -1. The detection limits of DZ and 7-OH-4-CHM was calculated as LOD DZ=0.08μM and LOD 7-OH-4-CHM=0.13μM  

We present an experimental investigation of stochastic switching of a bistable Josephson junction array resonator with a resonance frequency in the GHz range. As the device is in the regime where the anharmonicity is on the order of the linewidth, the bistability appears for a pump strength of only a few photons. We measure the dynamics of the bistability by continuously observing the jumps between the two metastable states, which occur with a rate ranging from a few Hz down to a few mHz. The switching rate strongly depends on the pump strength, readout strength and the temperature, following Kramers' theory. The interplay between nonlinearity and coupling, in this little explored regime,... 

The respiratory system is a vital organ system which makes breathing and gas exchange possible for human's body. The loss of functionality in this system is due to either genetical problems or environmental issues like pollution or toxic gases which in many cases is inevitable. These circumstances may cause different respiratory diseases which may not be curable presently but their side effects can be partly controlled by careful and timely analysis improving the quality of patient's life. So, an appropriate device for conducting different analysis can be effective for people who suffer from respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, occupational lung... 

Clioquinol is an antifungal, antiprotozoal and an Alzheimer's disease drug with cytotoxic activity toward human cancer cells. The electrochemical behavior of clioquinol and its oxidation product was studied using cyclic, differential pulse and square-wave voltammetry over a wide pH range on a glassy carbon electrode. The results revealed that the oxidation of clioquinol is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism and results in the formation of a main oxidation product, which adsorbs very strongly on the glassy carbon surface. The charge transfer coefficient was calculated as 0.64. The adsorbed... 

The electrochemical behaviour of temozolomide on a glassy carbon electrode has been investigated. The reduction of temozolomide is an irreversible process, pH dependent, and the mechanism involves the addition of one electron and one proton to C5 to form an anion radical, causing the irreversible breakdown of the tetrazinone ring. The oxidation mechanism of temozolomide is an irreversible, adsorption-controlled process, pH dependent up to value close to the pKa and occurs in two consecutive charge transfer reactions, with the formation of the hydroxylated product. The electroanalytical determination of TMZ led to a detection limit of 1.1 μM  

Recently, a new potential model has been proposed for the intermolecular interactions of model pure fluids and it was shown that the derived Equation Of State (EOS), based on this potential, can properly predict the thermodynamic properties of these.fluids. In addition to simplicity and, to some extent, the realistic form, this potential has a parameter (α) which controls the range of the attraction tail. In the first part of this study, the proposed potential and derived EOS are extended to binary mixtures of model fluids. In a similar manner to that of the pure fluids, the results obtained are consistent with the data available from simulation studies. In the second part, after... 

Traffic density estimation plays an integral role in intelligent transportation systems (ITS), using which provides important information for signal control and effective traffic management. In this paper, we present a new framework for traffic density estimation based on topic model, which is an unsupervised model. This framework uses a set of visual features without any need to individual vehicle detection and tracking, and discovers the motion patterns automatically in traffic scenes by using topic model. Then, likelihood value allocated to each video clip enables us to estimate its traffic density. Results on a standard dataset show high classification performance of our proposed... 

Traffic density estimation is one of the most challenging problems in Intelligent Transportation Systems. In this paper, we estimate the traffic flow density based on classification. Various new efficient features are introduced for distinguishing between different traffic states, including number of key-points, edges of difference-image and moving edges. These features describe the traffic flow without any need to individual vehicles detection and tracking. We experiment our proposed approach on a standard database and some real videos from Tehran roads. The results show high accuracy performance of our method, even in changes of environmental conditions (e.g., lighting), by using efficient... 

We present broad-band photometry of 11 planetary transits of the hot Jupiter WASP-74 b, using three medium-class telescopes and employing the telescope-defocusing technique. Most of the transits were monitored through I filters and one was simultaneously observed in five optical (U, g', r', i', z') and three near-infrared (J, H, K) passbands, for a total of 18 light curves. We also obtained new high-resolution spectra of the host star. We used these new data to review the orbital and physical properties of the WASP-74 planetary system. We were able to better constrain the main system characteristics, measuring smaller radius and mass for both the hot Jupiter and its host star than previously... 

This study aimed to investigate the variability in postural sway patterns during quiet standing in stroke survivors. The postural sway was measured in 19 stroke survivors, as well as 19 healthy demographically matched participants, at 3 levels of postural difficulty (rigid surface with closed and open eyes, and foam surface with closed eyes), and 3 levels of cognitive difficulty (without a cognitive task, easy and difficult cognitive tasks). Both linear analyses (the amount of postural sway variability, including the standard deviation of the COP velocity in both the anteroposterior (AP) and mediolateral (ML) directions), as well as non-linear analyses [the temporal structure of the COP... 

We have used molecular dynamics simulation to investigate hydrophilic– hydrophobic interfaces between calcium chloride (CaCl2) aqueous solutions and normal hexane. The results demonstrate the increasing impact of salt concentration on the liquid–liquid interfacial tension, hence, negative adsorption of CaCl2 according to Gibbs adsorption isotherm. Moreover, we calculated the density profiles of hexane, water, and the counter ions. The results reveal an electrical double layer near the interface and the less affinity of calcium cations toward the interface than that of chloride anions. Orientation of water molecules at the studied concentrations may result in developing a positively charged... 

This paper introduces an innovative adaptive controller based on the actor-critic method. The proposed approach employs the ink drop spread (IDS) method as its main engine. The IDS method is a new trend in softcomputing approaches that is a universal fuzzy modeling technique and has been also used as a supervised controller. Its process is very similar to the processing system of the human brain. The proposed actor-critic method uses an IDS structure as an actor and a 2-dimensional plane, representing control variable states, as a critic that estimates the lifetime goodness of each state. This method is fast, simple, and away from mathematical complexity. The proposed method uses the... 

In this paper the response of cantilevered reinforced concrete (RC) beams with smart rebars under static lateral loading has been numerically studied, using Finite Element Method. The material used in this study is SuperelasticShape Memory Alloys (SE SMAs) which contains nickel and titanium elements. The SE SMA is a unique alloy that has the ability to undergo large deformations and return to their undeformed shape by removal of stresses. In this study, different quantities of steel and smart rebars have been used for reinforcement andthe behavior of these models under lateral loading, including their load-displacement curves, residual displacements, and stiffness, were discussed. During... 

Plasmonic nanostructures offer great enhancement of the Raman signal due to the strong confinement of the electromagnetic field. Thus, they are considered as suitable candidates for surface enhanced Raman spectroscopy (SERS). In this work, we present an alternative fabrication route, called the glancing angle deposition (GLAD), for tunable fabrication of plasmonic self-organized Ag nanoparticle arrays aimed at SERS. Using the GLAD technique, the inter-particle distance within the arrays can be made as small as 1 nm. Moreover, the plasmonic resonance can be precisely tuned over the whole visible range. The GLAD method can be up-scaled; and when a transparent substrate is used, it enables... 

Sufficient quantity of trace metals is essential for a well performing anaerobic digestion (AD) process. Among the essential trace elements in active sites of multiple important enzymes for AD are iron and nickel ions. In the present study, iron and nickel in the form of Fe2O3 and NiO were coated on TiO2 nanoparticles to be used in batch and continuous operation mode. The effect of TiO2, Fe2O3–TiO2, and NiO–TiO2 nanoparticles on each step of AD process was assessed utilizing simple substrates (i.e. cellulose, glucose, acetic acid, and mixture of H2–CO2) as well as complex ones (i.e. municipal biopulp). The hydrolysis rate of cellulose substrate increased with higher dosages of the coated... 

In this article we report hydrogen sensing property of WO 3/MWNTs thin films that were fabricated by spin-coating on alumina substrates. The MWNTs were initially functionalized (f-MWNTs) to enhance dispersion in the sol of multiwalled carbon nanotubes (MWNTs) and tungsten trioxide (WO 3). Microstructure, morphology and chemical composition of the materials were characterized by SEM, TEM, XRD and XPS methods. Our results show WO 3 nanoparticles were nucleated on oxygenated group on surface of f-MWNTs in hybrid suspension. After annealing the films at 350 °C, electrical conductance measurements at different operating temperature were performed and the results indicates rather fast and linear... 

The partition constants of l-lysine HCl were measured in polymer-salt aqueous two-phase systems. These systems contain poly(ethylene glycol) with a nominal molecular weight of 4000 or 10000 and two different salts (dipotassium hydrogen phosphate or trisodium citrate 5-hydrate). The experimental data were obtained at temperatures of (293.15, 298.15, and 303.15) K. The effects of temperature, pH, polymer and salt concentrations, polymer molecular weight, and salt type on the partitioning of l-lysine HCl were also studied. The results showed that salt concentration has a significant effect on the partition constant while temperature has less effect. The Diamond and Hsu model was used to... 

Limited access to energy resources and increasing demand for mitigation of the environmental impacts have necessitated higher production efficiencies. Therefore, the promotion of R&D activities has been one of the main parts of national energy policies. In this research work, two methods are used for assessing the effectiveness of the R&D capital on resource conservation. First, by developing the resource-included knowledge production function of the energy sector and second, through direct assessment of the functionality of resource productivity from R&D capital. Based on official data provided by national statistical centers, a comparative analysis has been conducted to examine the... 

Here we analyze the effect of two relevant aspects related to cell preparation on quantum dot sensitized solar cells (QDSCs) performance: the architecture of the TiO 2 nanostructured electrode and the growth method of quantum dots (QD). Particular attention is given to the effect on the photovoltage, V oc, since this parameter conveys the main current limitation of QDSCs. We have analyzed electrodes directly sensitized with CdSe QDs grown by chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR). We have carried out a systematic study comprising structural, optical, photophysical and photoelectrochemical characterization in order to correlate the material... 

This paper introduces a novel scalable pipelined VLSI architecture for a 4×4 64-QAM hard-output multiple-input-multiple-output (MIMO) detector based on K-best lattice decoders. The key contribution is a means of expanding the intermediate nodes of the search tree on-demand, rather than exhaustively, along with three types of distributed sorters operating in a pipelined structure. The proposed architecture has a fixed critical path independent of the constellation size, on-demand expansion scheme, efficient distributed sorters, and is scalable to higher number of antennas. Fabricated in 0.13 μCMOS, it occupies 0.95 μ mm} 2 core area. Operating at 282 MHz clock frequency, it dissipates 135 mW...