Principal factors that determine the extension of detection range in molecular beacon aptamer/conjugated polyelectrolyte bioassays.

A strategy to extend the detection range of weakly-binding targets is reported that takes advantage of fluorescence resonance energy transfer (FRET)-based bioassays based on molecular beacon aptamers (MBAs) and cationic conjugated polyelectrolytes (CPEs). In comparison to other aptamer-target pairs, the aptamer-based adenosine triphosphate (ATP) detection assays are limited by the relatively weak binding between the two partners. In response, a series of MBAs were designed that have different stem stabilities while keeping the constant ATP-specific aptamer sequence in the loop part. The MBAs are labeled with a fluorophore and a quencher at both termini. In the absence of ATP, the hairpin MBAs can be opened by CPEs via a combination of electrostatic and hydrophobic interactions, showing a FRET-sensitized fluorophore signal. In the presence of ATP, the aptamer forms a G-quadruplex and the FRET signal decreases due to tighter contact between the fluorophore and quencher in the ATP/MBA/CPE triplex structure. The FRET-sensitized signal is inversely proportional to [ATP]. The extension of the detection range is determined by the competition between opening of the ATP/MBA G-quadruplex by CPEs and the composite influence by ATP/aptamer binding and the stem interactions. With increasing stem stability, the weak binding of ATP and its aptamer is successfully compensated to show the resistance to disruption by CPEs, resulting in a substantially broadened detection range (from millimolar up to nanomolar concentrations) and a remarkably improved limit of detection. From a general perspective, this strategy has the potential to be extended to other chemical- and biological-assays with low target binding affinity

Safe and Efficient Navigation of a Mobile Robot: Path Planning Based on Hierarchical Topology Map and Motion Planning with Pedestrian Behavior Model

Safety in mobile robot navigation is an essential aspect, but it is often accompanied by a trade-off of efficiency in different navigation steps. For global planning, safety is frequently handled by inflated obstacles. Larger margins to the obstacles increase safety while lessening the path efficiency, such as longer path length. For local motion planning tasks, safety becomes even more critical because of dynamic objects in the robot's proximity but also accompanies substantial trade-offs, such as highly low-speed operations. In such aspects of safety and efficiency, we propose safe and efficient global path planning and local motion planning methods. For global path planning, we proposed the allowable speed of navigation for safety, which limits the maximum speed based on the clearances in the environment. The corresponding cost formulates the traveling time, leading to planning a time-efficient global path. A new map representation is proposed, named Hierarchical Topology Map (HTM) and Hierarchical Topology Map with Explicit Corridor (HTM-EC), and incorporated with the proposed safety-aware navigation speed. HTM is a double-layered data structure of a topology graph and the corresponding metric skeleton points of a map, which returns a feasible, on-skeleton path in an extremely short time. HTM-EC is an extended map expression with the Explicit Corridor that incorporates the nearest obstacle points along with skeleton points into HTM, which returns an optimal, off-skeleton (i.e., metric) path with corridor optimization of the given on-skeleton path. When they are used together, safety-aware time-efficient paths can be planned with light computation. The efficacy of the safety-aware allowable speed and lighter computations have been verified with simulations and experiments. For local motion planning, we incorporate a pedestrian navigation model to address efficiency. The pedestrian model seeks the desired direction of motion that minimizes the remaining distance to the destination. The cognitive collision locations are computed, which enables far-sighted path planning by incorporating future configurations of the surroundings. Safety guarantee is analyzed for the output of the pedestrian-model-based motion planner. Finally, to address the behavioral uncertainties, the degree of cooperation (DoC) is proposed that helps prediction of the other objects' velocities with online estimation. The simulation results with the different number of agents show that the pedestrian model can generate a smooth path between the agents. As the local planner uses fixed-length visual measurement such as LiDAR, the proposed planner is scalable regardless of the number of moving obstacles as well as the types of obstacles (i.e., static or dynamic)

Sharing tacit design knowledge in a distributed design environment

Throughout the life-cycle of a design project, architects rely heavily on their tacit design knowledge to support design decisions. Tacit knowledge is highly personal and implicit. As such, it encompasses expertise, intuitive understanding, and professional insight formed as a result of experience. Due to its implicit nature, tacit design knowledge is typically shared only among colleagues who work in the same office through face-toface interactions. With emerging Computer-Mediated Communication (CMC) technologies, designers face new opportunities for capturing and reusing tacit design knowledge. However, there is no accepted CMC strategy for sharing tacit design knowledge in the Architecture, Engineering, and Construction (AEC) industry. This research investigates the impact of tacit design knowledge on design performance in a distributed design environment supported by CMC software. The software was developed and tested in three design studios in which design students sought advice from experts in remote locations. It provides tools for showing images, such as drawings and renderings, and for engaging in a written dialogue (chat session). The written and graphic artifacts of the conversation are stored in a Web-accessible database. The chat sessions included the identification, clarification, and explanation of real problems. Dialogue records provide evidence of a significant influence upon the studentsâ approach to conceptual design. Content analysis of the comments from the experts provides qualitative evidence for the softwareâÂÂs effectiveness. The participants shared past experience, professional recommendations, and intuitive expectations. In follow-up surveys, most participants reported that their experience with the software was very enjoyable and the software is well-designed to support sharing of design knowledge. This research also suggests that tacit design knowledge may be confidently captured and shared through careful strategic implementation of CMC technology in a distributed design environment. Demographic and attitudinal surveys of the participants suggest that enabling factors for sharing tacit design knowledge include knowledge sharing attitude, just-in-time expertise matching, and timing of the communication

Surface Sr segregation behaviors in a model thin film perovskite cathode for solid oxide fuel cells

Surface cation segregation, strontium (Sr) in particular, has been considered as one of crucial barriers to achieving a fast surface oxygen exchange rate of perovskite oxide electrodes for solid oxide fuel cells (SOFCs). However, the major driving force for the segregation phenomenon still remains unknown, and thus it is also unknown how to maximize the cathode performance. In this work, we fabricated epitaxial thin films of SrTi1-xFexO3-δ (STF) via pulsed laser deposition (PLD) and quantitatively characterized their microstructures, surface chemical compositions and oxygen exchange rates by a range of analysis tools, in this case HR-TEM, HR-XRD, angle resolved X-ray photoelectron spectroscopy (AR-XPS) and electrical conductivity relaxation (ECR). The use of well-defined epitaxial thin films not only guarantees high precision, reproducibility and reliability of the surface properties, but also enables us to control the degree of misfit strain by varying the choice of the substrate and the target composition. This, in combination with density functional theory (DTF) simulation, enabled to reveal a close relationship between the degree of surface Sr segregation and the misfit strain and thereby to identify the governing factors for the Sr segregation phenomenon

HOW E-COMMERCE IS CHANGING THE FACILITY MANAGEMENT PRACTICES OF BUILDING OWNERS

"The corporate Ford of 2010 will look more like Cisco, a company that manufactures very little.” "Direct-to-the-assembly-line ordering will enable Ford to custom configure cars much the way that Dell custom configures computers.” --Forbes, July 17, 2000 The above quotation is an indication of how information technology is changing even old-line manufacturing organizations. The research reported in this paper was motivated by our desire to better understand how information technology and, in particular, the recent phenomenon of e-commerce, was influencing the design and construction industry. Since trends in the building industry are often determined by the desires and programs initiated by large building owners, we decided to focus our research on facility management organizations in Fortune-500 companies

‘Evidence of an auxin signal pathway, microRNA167-ARF8-GH3, and its response to exogenous auxin in cultured rice cells’

MicroRNA167 (miR167) was shown to cleave auxin responsive factor 8 (ARF8) mRNA in cultured rice cells. MiR167 level was found to be controlled by the presence of auxin in the growth medium. When cells grew in auxin-free medium, miR167 level decreased, resulting in an increase in the level of ARF8 mRNA. Cells growing in the normal growth medium containing auxin showed a reversed trend. It was also shown that expression of OsGH3-2, an rice IAA-conjugating enzyme, was positively regulated by ARF8. Delivery of synthesized miR167 into cells led to decrease of both ARF8 mRNA and OsGH3-2 mRNA. This study provides an evidence in which the exogeneous auxin signal is transduced to OsGH3-2 through miR167 and ARF8 in sequence. This proposed auxin signal transduction pathway, auxin-miR167-ARF8-OsGH3-2, could be, in conjunction with the other microRNA-mediated auxin signals, an important one for responding to exogeneous auxin and for determining the cellular free auxin level which guides appropriate auxin responses

In situ-prepared composite materials of PEDOT: PSS buffer layer-metal nanoparticles and their application to organic solar cells

We report an enhancement in the efficiency of organic solar cells via the incorporation of gold (Au) or silver (Ag) nanoparticles (NPs) in the hole-transporting buffer layer of poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), which was formed on an indium tin oxide (ITO) surface by the spin-coating of PEDOT:PSS-Au or Ag NPs composite solution. The composite solution was synthesized by a simple in situ preparation method which involved the reduction of chloroauric acid (HAuCl4) or silver nitrate (AgNO3) with sodium borohydride (NaBH4) solution in the presence of aqueous PEDOT:PSS media. The NPs were well dispersed in the PEDOT:PSS media and showed a characteristic absorption peak due to the surface plasmon resonance effect. Organic solar cells with the structure of ITO/PEDOT:PSS-Au, Ag NPs/poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PC61BM)/LiF/Al exhibited an 8% improvement in their power conversion efficiency mainly due to the enlarged surface roughness of the PEDOT:PSS, which lead to an improvement in the charge collection and ultimately improvements in the short-circuit current density and fill factor. © 2012 Woo et al.1