Extremely Vivid,Highly Transparent,and Ultrathin Quantum Dot Light‐Emitting Diodes

Displaying information on transparent screens offers new opportunities in next‐generation electronics, such as augmented reality devices, smart surgical glasses, and smart windows. Outstanding luminance and transparency are essential for such “see‐through” displays to show vivid images over clear background view. Here transparent quantum dot light‐emitting diodes (Tr‐QLEDs) are reported with high brightness (bottom: ≈43 000 cd m^?2, top: ≈30 000 cd m^?2, total: ≈73 000 cd m^?2 at 9 V), excellent transmittance (90% at 550 nm, 84% over visible range), and an ultrathin form factor (≈2.7 µm thickness). These superb characteristics are accomplished by novel electron transport layers (ETLs) and engineered quantum dots (QDs). The ETLs, ZnO nanoparticle assemblies with ultrathin alumina overlayers, dramatically enhance durability of active layers, and balance electron/hole injection into QDs, which prevents nonradiative recombination processes. In addition, the QD structure is further optimized to fully exploit the device architecture. The ultrathin nature of Tr‐QLEDs allows their conformal integration on various shaped objects. Finally, the high resolution patterning of red, green, and blue Tr‐QLEDs (513 pixels in.^?1) shows the potential of the full‐color transparent display.     

Simulation study on discrete charge effects of SiNW biosensors according to bound target position using a 3D TCAD simulator

We introduce a simulation method for the biosensor environment which treats the semiconductor and the electrolyte region together, using the well-established semiconductor 3D TCAD simulator tool. Using this simulation method, we conduct electrostatic simulations of SiNW biosensors with a more realistic target charge model where the target is described as a charged cube, randomly located across the nanowire surface, and analyze the Coulomb effect on the SiNW FET according to the position and distribution of the target charges. The simulation results show the considerable variation in the SiNW current according to the bound target positions, and also the dependence of conductance modulation on the polarity of target charges. This simulation method and the results can be utilized for analysis of the properties and behavior of the biosensor device, such as the sensing limit or the sensing resolution.     

Efficient operation methods for a component placement machine using the patterns on printed circuit boards

Operation of a PCB assembler is complicated to optimise since it requires simultaneous consideration of a component's rack assignment and component mounting sequencing. However, most previous researches considered the constraints separately on the optimisation process. Two different methods using special features on printed circuit boards are developed and presented in this research. Based on results from field surveys, it is found that identical components are positioned closely with each other or identical single boards are repeatedly printed on one big board to enlarge up to a proper size to be assembled in the machine. These patterns are adapted on the design of assembly methods to increase productivity. Simulation models are constructed using Visual C++ for performance evaluation purposes of the developed heuristics.     

Flight path optimization passing through waypoints for autonomous flight control systems

Trajectory optimization is performed to generate a flight path passing specified waypoints. To deal with the unspecified time of passing through a waypoint, an auxiliary variable is introduced. Normalization of the time variable by the auxiliary variable transforms the waypoint optimization problem into the conventional optimization problem. The condition for passing through the waypoints can be relaxed, so that the vehicle passes specified waypoints within a certain acceptable range. Sequential quadratic programming is used to solve the optimization problem. As a numerical example, six degree-of-freedom vehicle dynamics is considered. Two-dimensional and three-dimensional trajectory optimization problems with several waypoints are solved to verify the effectiveness of the proposed algorithm.     

Transient SHG Imaging on Ultrafast Carrier Dynamics of MoS2 Nanosheets

Understanding the collaborative behaviors of the excitons and phonons that result from light–matter interactions is important for interpreting and optimizing the underlying fundamental physics at work in devices made from atomically thin materials. In this study, the generation of exciton‐coupled phonon vibration from molybdenum disulfide (MoS₂) nanosheets in a pre‐excitonic resonance condition is reported. A strong rise‐to‐decay profile for the transient second‐harmonic generation (TSHG) of the probe pulse is achieved by applying substantial (20%) beam polarization normal to the nanosheet plane, and tuning the wavelength of the pump beam to the absorption of the A‐exciton. The time‐dependent TSHG signals clearly exhibit acoustic phonon generation at vibration modes below 10 cm^?1 (close to the Γ point) after the photoinduced energy is transferred from exciton to phonon in a nonradiative fashion. Interestingly, by observing the TSHG signal oscillation period from MoS₂ samples of varying thicknesses, the speed of the supersonic waves generated in the out‐of‐plane direction (Mach 8.6) is generated. Additionally, TSHG microscopy reveals critical information about the phase and amplitude of the acoustic phonons from different edge chiralities (armchair and zigzag) of the MoS₂ monolayers. This suggests that the technique could be used more broadly to study ultrafast physics and chemistry in low‐dimensional materials and their hybrids with ultrahigh fidelity.     

Facilitated Water Transport through Graphene Oxide Membranes Functionalized with Aquaporin‐Mimicking Peptides

Water purification by membranes is widely investigated to address concerns related to the scarcity of clean water. Achieving high flux and rejection simultaneously is a difficult challenge using such membranes because these properties are mutually exclusive in common artificial membranes. Nature has developed a method for this task involving water‐channel membrane proteins known as aquaporins. Here, the design and fabrication of graphene oxide (GO)‐based membranes with a surface‐tethered peptide motif designed to mimic the water‐selective filter of natural aquaporins is reported. The short RF8 (RFRFRFRF, where R and F represent arginine and phenylalanine, respectively) octapeptide is a concentrated form of the core component of the Ar/R (aromatic/arginine) water‐selective filter in aquaporin. The resulting GO‐RF8 shows superior flux and high rejection similar to natural aquaporins. Molecular dynamics simulation reveal the unique configuration of RF8 peptides and the transport of water in GO‐RF8 membranes, supporting that RF8 effectively emulates the core function of aquaporins.     

The application of non-parametric statistical techniques to an ALARA programme

For the cost-effective reduction of occupational radiation dose (ORD) at nuclear power plants, it is necessary to identify what are the processes of repetitive high ORD during maintenance and repair operations. To identify the processes, the point values such as mean and median are generally used, but they sometimes lead to misjudgment since they cannot show other important characteristics such as dose distributions and frequencies of radiation jobs. As an alternative, the non-parametric analysis method is proposed, which effectively identifies the processes of repetitive high ORD. As a case study, the method is applied to ORD data of maintenance and repair processes at Kori Units 3 and 4 that are pressurised water reactors with 950 MWe capacity and have been operating since 1986 and 1987 respectively, in Korea and the method is demonstrated to be an efficient way of analysing the data.