Local structure and medium-range ordering in relaxor ferroelectric Pb(Zn <inf>1/3</inf>Nb <inf>2/3</inf>)O <inf>3</inf> studied using neutron pair distribution function analysis

We studied an evolution of local structure and medium-range ordering in relaxor ferroelectric Pb(Zn 1/3Nb 2/3)O 3 (PZN) from 550 to 15 K using neutron pair distribution function analysis. We show that the local structure of PZN is distorted at all temperatures studied. With decreasing temperature, a medium-range ordering of local polarizations develops with no global rhombohedral phase transition below T M. Instead, the crystal structure can be described as a mixture of polar nanoregions in a disordered lattice, similar to the case of Pb(Mg 1/3Nb 2/3)O 3. © 2006 American Institute of Physics

Measurement of diffusion in articular cartilage using fluorescence correlation spectroscopy

<p>Abstract</p> <p>Background</p> <p>Fluorescence correlation spectroscopy (FCS) provides information about translational diffusion of fluorescent molecules in tiny detection volumes at the single-molecule level. In normal states, cartilage tissue lacks vascularity, so chondrocyte metabolism depends on diffusion for molecular exchanges. The abundant extracellular matrix (ECM) of cartilage is maintained by a limited number of chondrocytes. ECM plays an important role in the regulation of chondrocyte functions. In this study, FCS was used to measure diffusion behaviors of albumin, the major protein of the intra-articular space, using normal and degenerated cartilage. Preliminary investigation of fluorescence dyes including Alexa 488, Rhodamine 6G and Rhodamine 123 was conducted to evaluate their properties in cartilage.</p> <p>Results</p> <p>The results indicate that the diffusion behaviors of fluorescently lableded albumin can be observed using FCS in both normal and chemically degenerated cartilage.</p> <p>Conclusions</p> <p>This work demonstrates the capability of FCS for direct measurement of diffusion in cartilaginous ECM. When the diffusion characteristics of fluorescent probes in ECM are clarified using FCS evaluation, FCS will be applicable as a method for early diagnosis of osteoarthritis, which is accompanied by increased abnormalities of ECM and also as tool for evaluating bio-engineered artificial cartilage for autologous chondrocyte implantation.</p

Charge ordering, ferroelectric, and magnetic domains in LuFe2O4 observed by scanning probe microscopy

LuFe2O4 is a multiferroic system which exhibits charge order, ferroelectricity, and ferrimagnetism simultaneously below similar to 230 K. The ferroelectric/charge order domains of LuFe2O4 are imaged with both piezoresponse force microscopy (PFM) and electrostatic force microscopy (EFM), while the magnetic domains are characterized by magnetic force microscopy (MFM). Comparison of PFM and EFM results suggests that the proposed ferroelectricity in LuFe2O4 is not of usual displacive type but of electronic origin. Simultaneous characterization of ferroelectric/charge order and magnetic domains by EFM and MFM, respectively, on the same surface of LuFe2O4 reveals that both domains have irregular patterns of similar shape, but the length scales are quite different. The domain size is approximately 100 nm for the ferroelectric domains, while the magnetic domain size is much larger and gets as large as 1 mu m. We also demonstrate that the origin of the formation of irregular domains in LuFe2O4 is not extrinsic but intrinsic. (c) 2015 AIP Publishing LLC.open11116sciescopu

Adaptive Fuzzy Dynamic Surface Sliding Mode Position Control for a Robot Manipulator with Friction and Deadzone

Precise tracking positioning performance in the presence of both the deadzone and friction of a robot manipulator actuator is difficult to achieve by traditional control methodology without proper nonlinear compensation schemes. In this paper, we present a dynamic surface sliding mode control scheme combined with an adaptive fuzzy system, state observer, and parameter estimator to estimate the uncertainty, friction, and deadzone nonlinearities of a robot manipulator system. We design a dynamic surface sliding mode basic controller by systematic recursive design steps that yields several adaptive laws for the compensation of nonlinear friction, deadzone, and other unknown nonlinear dynamics. The boundedness and convergence of this closed-loop system are guaranteed by the Lyapunov stability theorem. Experiments on the Scorbot robot manipulator demonstrate the validity and effectiveness of the proposed control scheme

Transparent organic light-emitting diodes with different bi-directional emission colors using color-conversion capping layers

We report a study on transparent organic light-emitting diodes (OLEDs) with different bidirectional emission colors, enabled by color-conversion organic capping layers. Starting from a transparent blue OLED with an uncapped Ag top electrode exhibiting an average transmittance of 33.9%, a 4-(Dicyanomethylene)-2-methyl- 6-(4-dimethylaminostyryl)-4Hpyran (DCM)-doped tris-(8-hydroxy-quinolinato)-aluminium (Alq3) capping layer is applied to achieve color-conversion from blue to orange-red on the top side while maintaining almost unchanged device transmittance. This color-conversion capping layer does not only change the color of the top side emission, but also enhances the overall device efficiency due to the optical interaction of the capping layer with the primary blue transparent OLED. Top white emission from the transparent bi-directional OLED exhibits a correlated color temperature around 6,000K-7,000K, with excellent color stability as evidenced by an extremely small variation in color coordinate of ∆(x,y) = (0.002, 0.002) in the forward luminance range of 100-1000 cd m-2. At the same time, the blue emission color of bottom side is not influenced by the color conversion capping layer, which finally results in different emission colors of the two opposite sides of our transparent OLEDsPostprintPeer reviewe