New immunoassay platform utilizing yeast surface display and direct cell counting

In this study, we report a new immunoassay platform using yeast cell surface display. This method holds promise for very low limit of detection (LOD) and is suitable for 2-Plex antibody recognition. Instead of adopting a conventional enzyme linked immunosorbent assay (ELISA) protocol by detecting the enzymatic activities or other physicochemical properties of the labeled analytes, this approach determines the quantity of an antibody analyte by directly counting the amount of "modified" yeast cells bound with antibody on the cell surface. c-myc and hemagglutinin (HA) tags were employed as an epitope model to demonstrate our approach. This yeast surface display based cell counting immunoassay (abbreviated as YSD-CCI) for anti-c-myc has a detection limit of 0.2 ng/mL, which is about 80 times higher than that of a conventional yeast ELISA under a similar condition. Moreover, the YSD-CCI's capability for 2-Plex antibody detection was demonstrated by simultaneous detection of anti-c-myc and anti-HA using engineered yeast cells expressing intracellular enhanced green fluorescent protein (EGFP) and mCherry, respectively. This proof-of-concept study paves the way for a new ultrasensitive multiplexed immunoassay method for diagnostic applications.     

Josephson Current in a Gapped Graphene Superconductor/Barrier/Superconductor Junction: Case of Massive Electrons

The Josephson effect in a gapped graphene-based superconductor/barrier/superconductor junction is studied. The superconductivity in gapped graphene may be achieved by depositing conventional superconductor on the top of the gapped graphene such as graphene grown on SiC substrate. In gapped graphene system, the carriers exhibit massive Dirac fermions. We focus on the effect of pseudo-Dirac-like mass on the supercurrent. In contrast to that in the gapless graphene superconductor/barrier/superconductor junction, we find that the supercurrent exhibits dependency of the Fermi energy. Also, the massive supercurrent anomalously oscillates as a function of the gate potential. This novel behavior is due to the effect of electrons acquiring mass in gapped graphene.     

提高微型气体传感器可靠性的有效方法-解决氧化锡敏感膜龟裂问题

本文报导了一种解决氧化锡气体敏感膜龟裂问题的有效方法.实验中发现,溅射形成的氧化锡薄膜在高温处理后或在长时间的高温工作中会发生龟裂,对器件的稳定性和可靠性带来很大影响.我们用两种方法解决了这个问题.一个是用磷硅玻璃(PSG)回流对氧化锡衬底的粗糙表面进行平坦化处理,另一个是把氧化锡薄膜图形设计成许多细长条状,以释放高温引起的应力变化.这种技术也适用于其它薄膜产生的微裂问题.     

Ultrasensitive solution-phase electrochemical molecular beacon-based DNA detection with signal amplification by exonuclease III-assisted target recycling

Taking advantage of the preferential exodeoxyribonuclease activity of exonuclease III in combination with the difference in diffusivity between an oligonucleotide and a mononucleotide toward a negatively charged ITO electrode, a highly sensitive and selective electrochemical molecular beacon (eMB)-based DNA sensor has been developed. This sensor realizes electrochemical detection of DNA in a homogeneous solution, with sensing signals amplified by an exonuclease III-based target recycling strategy. A hairpin-shaped oligonucleotide containing the target DNA recognition sequence, with a methylene blue tag close to the 3' terminus, is designed as the signaling probe. Hybridization with the target DNA transforms the probe's exonuclease III-inactive protruding 3' terminus into an exonuclease III-active blunt end, triggering the digestion of the probe into mononucleotides including a methylene blue-labeled electro-active mononucleotide (eNT). The released eNT, due to its less negative charge and small size, diffuses easily to the negative ITO electrode, resulting in an increased electrochemical signal. Meanwhile, the intact target DNA returns freely to the solution and hybridizes with other probes, releasing multiple eNTs and thereby further amplifies the electrochemical signal. This new immobilization-free, signal-amplified electrochemical DNA detection strategy shows great potential to be integrated in portable and cost-effective DNA sensing devices.     

Singularity analysis of three-legged, six-DOF platform manipulators with URS legs

A special class of platform manipulators is the subject of this paper. These manipulators comprise two platforms connected by three legs, each being composed of one universal (U), one revolute (R) and one spherical (S) joints, which gives the manipulator six degrees of freedom. Hence, two actuators are required per leg. Under the assumption that the two R joints proximal to the fixed platform, and making up the U-joint, are actuated, we derive the differential kinematic relations between actuator joint rates and mobile-platform twist. This model comprises two Jacobian matrices, the forward- and inverse-kinematics Jacobians. These relations are then applied to the singularity analysis of the parallel manipulator developed at Singapore Institute of Manufacturing Technology and Nanyang Technological University.     

The effects of doped Nd on conductivity and phase stability of BaCe0.8Y0.2O3−δ-based electrolyte for solid oxide fuel cell

This study investigates the structure, phase stability, and electrical properties of BaCe_0.8Y_0.2−xNd_xO_3−δ (x = 0-0.2) in humid air. XRD results indicate that a BaCe_0.8Y_0.2−xNd_xO_3−δ sample has an asymmetric orthorhombic structure, and this structure becomes more symmetric as the amount of Nd doping increases. The conductivity of BaCe_0.8Y_0.2−xNd_xO_3−δ depends on the amount of Nd doping and the operation temperature. AC impedance results indicate that the resistance of BaCe_0.8Y_0.2−xNd_xO_3−δ decreases as the temperature increases, with the majority of resistance coming from oxygen ion diffusion. The XRD peak intensity of BaCe_0.8Y_0.2O_3−δ apparently decreased with time, forming Ba(OH)₂ and CeO₂ second phases. The phase stability of BaCe_0.8Y_0.2−xNd_xO_3−δ (x = 0.05-0.2) samples is much better than that of BaCe_0.8Y_0.2O_3−δ, and it exhibited no second phase after tested in an 80 °C water bath for 18 h.     

A process for simultaneously achieving phenol biodegradation and polyhydroxybutyrate accumulation using <Emphasis Type="Italic">Cupriavidus taiwanesis</Emphasis> 187

Cupriavidus taiwanensis 187 is reportedly efficient in achieving the degradation of phenol and accumulation of polyhydroxybutyrate (PHB). This study attempted to optimize the cultivation conditions and fermentation strategies for phenol degradation and PHA accumulation by C. taiwanensis 187. After the cultivation conditions were optimized, the conditions required for achieving phenol degradation (100%) and PHB accumulation (51 mg/L) by C. taiwanensis 187 were identified as 30 °C and 200 rpm, when the cultivation time was around 7 h. The accumulation of PHB was further increased from 72 to 213 mg/L by feeding phenol in three rounds into the fermenter along with the exhaustion of dissolved oxygen, which could totally degrade the phenol at around 1500 mg/L. Production of PHB by C. taiwanensis 187 was confirmed by GC, ¹H-NMR, and ¹³C-NMR analyses. Each analytical result proved that C. taiwanensis 187 was able to use phenol as the sole carbon source for producing PHB. Finally, these results revealed that the phenol degraded by C. taiwanensis 187 mainly contributed to cell growth rather than PHB accumulation. These results indicated that the strain C. taiwanensis 187 could be used to degrade phenol to obtain usable biological polyesters.     

Integrated design of legged mechatronic system

This paper presents a system based on the integrated design and experiment for a one degree-of-freedom (DOF) legged mechatronic system (LMTS). A six-bar linkage mechanism, which is derived from a four-bar linkage with a symmetrical coupler point and pantograph into one, is designed, and common controllers are used to control the velocity and position loops. For system-based dynamic optimization, the design for control (DFC) approach is used to integrate the structure and control for improving dynamic performance with reduced control torque. Finally, for a rapid 3D graphical based implementation of the system, high-level computer-aided rapid system integration (CARSI) technology is used to integrate the structure design, controller design, and system implementation into the design and analytical software environment based on Pro/engineer, XML syntax, Simmechanics, and Simulink. Thus, the development time for the LMTS is reduced.     

Spatial learning in a virtual multilevel building: Evaluating three exocentric view aids

The present study explores how the design of the exocentric view aid affects the acquisition of survey knowledge in virtual environments. The exocentric view was provided by either a 3D floor map, a 3D building map or the elevation of viewpoint in air. Participants navigated a virtual multilevel building and their survey knowledge was measured by the judgment of spatial relative direction. The results showed that (1) the accuracy of spatial judgment along the horizontal direction and response time were improved for participants with the exocentric view aid; (2) the accuracy of spatial judgment along the vertical direction was worst in the condition with a 3D floor map; (3) in general participants with a 3D building map performed best. The data suggested that the large scale of an exocentric view aid and the increased number of exocentric perspective through which the spatial layout is observed can facilitate the acquisition of survey knowledge in a virtual building. Potential applications of the findings include the design of a 3D map for navigation in both real and virtual buildings.