2,932 research outputs found

    Microcantilever based on flavoenzyme monoamine oxidase (MAO) as a bioprobe

    Get PDF
    Microcantilevers (MCLs) are cost-effective and highly sensitive devices for biodetection. Adsorption of specific analytes on the microcantilever surface causes the bending of MCL through changing of the surface characteristics. These new bioprobes designed in a way that one side of the microcantilever surface is coated with a selective receptor that absorbs particular molecules. After surface absorption of target, the microcantilever deflects under nano – Newton forces and results in microcantilever bending. In the following work, we have proposed a modifed microcantilever through immobilization of monoamine oxidase (MAO) as a Flavin–Adenosine-Dinucleotide (FAD)-containing enzyme. This enzyme catalyzes the oxidative deamination of amine groups, so interaction between compounds with amine functional group and enzyme is based on biodetection with monoamine oxidase modified microcantilever. In the present study, MAO was immobilized on the microcantilever surface through a cross linker to a monolayer on the gold surface. Following, the Kynuramine solution was used as substrate. The comparative results showed that the enzyme is activated in immobilized state in order to oxidize amine groups and is inhibited in the presence of Methamphethamine as an enzyme inhibitor. Since all processes are performing at room temperature, therefore the design of bioprobe based on modified microcantilever would be highly significant for biodetection

    Digital Holographic Microscopy of Phase Separation in Multicomponent Lipid Membranes

    Get PDF
    Lateral in-homogeneities in lipid compositions cause microdomains formation and change in the physical properties of biological membranes. With the presence of cholesterol and mixed species of lipids, phospholipid membranes segregate into lateral domains of liquid-ordered and liquid-disordered phases. Coupling of two-dimensional intralayer phase separations and interlayer liquid-crystalline ordering in multicomponent membranes has been previously demonstrated. By the use of digital holographic microscopy (DHMicroscopy), we quantitatively analyzed the volumetric dynamical behavior of such membranes. The specimens are lipid mixtures composed of sphingomyelin, cholesterol, and unsaturated phospholipid, 1,2-dioleoyl-sn-glycero-3-phosphocholine. DHMicroscopy in a transmission mode is an effective tool for quantitative visualization of phase objects. By deriving the associated phase changes, three-dimensional information on the morphology variation of lipid stacks at arbitrary time scales is obtained. Moreover, the thickness distribution of the object at demanded axial planes can be obtained by numerical focusing. Our results show that the volume evolution of lipid domains follows approximately the same universal growth law of previously reported area evolution. However, the thickness of the domains does not alter significantly by time; therefore, the volume evolution is mostly attributed to the changes in area dynamics. These results might be useful in the field of membrane-based functional materials

    Modeling anisotropic and rate-dependent plasticity in short-fiber reinforced thermoplastics

    Get PDF
    In this study, an anisotropic viscoelastic-viscoplastic macro-mechanical model is presented for short-fiber reinforced thermoplastics (SFRT). In injection molding of SFRT, the fiber orientation is influenced by the flow velocity profile which varies throughout the mold. The flow-induced orientation in the microstructure leads to anisotropy in the mechanical response. In addition to the mechanical anisotropy, SFRTs show time dependent behavior because of the thermoplastic matrix. The developed model captures the effects of both material orientation and loading rate on the yield behavior. In this study, uniaxial tests are performed at different strain rates and material orientations with samplescutfrominjectionmoldedplaques. Theexperimentalresultsshowthattheeffects of loading rate and material orientation on the yield are decoupled. The presented model takes advantage of this observation to simplify material characterization. An implicit integration scheme is used for the numerical implementation of the model as a UMAT in ABAQUS. Multiple relaxation times are used in order to capture the nonlinear pre-yield regime. An efficient method for obtaining the model parameters for different modes is proposed. Experimental results are used for validation of the model and a good agreement is observed for the prediction of viscoelastic and viscoplastic behavior

    A Doorway Detection and Direction (3Ds) System for Social Robots via a Monocular Camera

    Get PDF
    In this paper, we propose a novel algorithm to detect a door and its orientation in indoor settings from the view of a social robot equipped with only a monocular camera. The challenge is to achieve this goal with only a 2D image from a monocular camera. The proposed system is designed through the integration of several modules, each of which serves a special purpose. The detection of the door is addressed by training a convolutional neural network (CNN) model on a new dataset for Social Robot Indoor Navigation (SRIN). The direction of the door (from the robot’s observation) is achieved by three other modules: Depth module, Pixel-Selection module, and Pixel2Angle module, respectively. We include simulation results and real-time experiments to demonstrate the performance of the algorithm. The outcome of this study could be beneficial in any robotic navigation system for indoor environments

    A Brain-Inspired Multi-Modal Perceptual System for Social Robots: An Experimental Realization

    Get PDF
    We propose a multi-modal perceptual system that is inspired by the inner working of the human brain; in particular, the hierarchical structure of the sensory cortex and the spatial-temporal binding criteria. The system is context independent and can be applied to many on-going problems in social robotics, including but not limited to person recognition, emotion recognition, and multi-modal robot doctor to name a few. The system encapsulates the parallel distributed processing of real-world stimuli through different sensor modalities and encoding them into features vectors which in turn are processed via a number of dedicated processing units (DPUs) through hierarchical paths. DPUs are algorithmic realizations of the cell assemblies in neuroscience. A plausible and realistic perceptual system is presented via the integration of the outputs from these units by spiking neural networks. We will also discuss other components of the system including top-down influences and the integration of information through temporal binding with fading memory and suggest two alternatives to realize these criteria. Finally, we will demonstrate the implementation of this architecture on a hardware platform as a social robot and report experimental studies on the system

    Robust Nash Dynamic Game Strategy for User Cooperation Energy Efficiency in Wireless Cellular Networks

    Get PDF
    Recently, there is an emerging trend of addressing “energy efficiency” aspect of wireless communications. It has been shown that cooperating users relay each other\u27s information to improve data rates. The energy is limited in the wireless cellular network, but the mobile users refuse to relay. This paper presents an approach that encourages user cooperation in order to improve the energy efficiency. The game theory is an efficient method to solve such conflicts. We present a cellular framework in which two mobile users, who desire to communicate with a common base station, may cooperate via decode-and-forward relaying. In the case of imperfect information assumption, cooperative Nash dynamic game is used between the two users\u27 cooperation to tackle the decision making problems: whether to cooperate and how to cooperate in wireless networks. The scheme based on “cooperative game theory” can achieve general pareto-optimal performance for cooperative games, and thus, maximize the entire system payoff while maintaining fairness

    Evaluation of Anti-ulcer Activity of Echinops Persicus on Experimental Gastric Ulcer Models in Rats

    Get PDF
    Extract of Echinops persicus is traditionally used for a long time in Iran for treatment of cough and constipation. This extract is produced by activity of bug (Situphilus spp.) on the plant. We documented its anti-tussive effect in rats in our previous study.The aim of this study was to assess the anti-ulcer effect of Echinops persicus in an animal model. In this study we evaluated anti-ulcer effect of Echinops persicus by Shay's method in rats. In 3 groups of rats, pylorus was ligatured under anesthesia. The rats were euthanized after 19 hours later and number and level of ulcer in stomach was measured. In group 2 the extract was orally administered 45 minutes before pyloric ligature, and in group 3, it was administered intraperitoneally 20 minutes before pyloric ligature. The number of ulcers in stomach was significantly low in group 2 (P = 0.01) and 3 (P = 0.037) in comparison with group 1. The level of ulcer was significantly decreased in group 2 (P = 0.047) with comparison to group 1. We conclude that, Echinops extract can exhibit potentially cytoprotective and anti-ulcer activity

    Assay of Bacteriorhodopsin Activity and Structure on Polycarbonate Surface by Spin Coating Method and Photochemical Activity Analysis

    Get PDF
    Introduction: Protein-based memory is a novel technology that employs proteins ability to participate in electronic processes. Bacteriorhodopsin (BR) is a membranous proton pump that it’s applications in bio-molecular electronic devices has been widely studied. The results of this research show that BR bounded to modified polycarbonate surface has higher activity for spin coating method.Materials and Methods: In an in-vitro study, BR-containing polymer matrix of polyvinyl alcohol and gelatin with different w/v ratios was prepared. Spectroscopic and enzyme activity analysis was performed and the optimized concentration for BR-containing films was determined to be 3.2 mg/ml. BR-polymer was then immobilized on the polycarbonate surface with spin coating method and AFM microscopy was used to characterize BR-coated polycarbonate.Results: Based on the obtained results we conclude that polymer concentrations below 1% significantly reduced BR activity levels. A280/A570 of 3.64 for 3.2 mg/ml BR solution and 4.97 for BR in 1% polymer confirmed the quality prepared film. AFM study of BR-coated polycarbonate surface revealed the overall thickness of 25nm, indicating that we were able to prepare a surface with suitable thickness for nano electronic devicesConclusion: The results of this research show that BR bounded to modified polycarbonate surface has higher activity for spin coating method. 

    Direct electron transfer of laccase enzyme based on RGO/AuNPs/PNR

    Get PDF
    Biofuel cell has been received much attention in recent years because the global energy demand increases every year. This paper presents a design of  Mytheliophthora thermophile laccase on the electrode as a biocathode for biofuel cells based on direct electron transfer (DET) between the active site of the enzyme and reduced graphene oxide-gold nanoparticles-poly neutral red (RGO/AuNPs/PNR). The RGO/AuNPs/PNR/laccase biocathode was characterized by cyclic voltammetry (CV) method. The CV experiments demonstrated the activity, direct electron transfer, and stability of immobilized enzyme on the nanocomposite. The results showed the immobilized enzyme had good stability and performance on the nanocomposite after 10 days. Therefore, the presented method would be used in the design of biosensors or biocathode of biofuel cells
    corecore