Heterogeneous Integration of Carbon‐Nanotube–Graphene for High‐Performance,Flexible, and Transparent Photodetectors

Low‐dimensional carbon materials, such as semiconducting carbon nanotubes (CNTs), conducting graphene, and their hybrids, are of great interest as promising candidates for flexible, foldable, and transparent electronics. However, the development of highly photoresponsive, flexible, and transparent optoelectronics still remains limited due to their low absorbance and fast recombination rate of photoexcited charges, despite the considerable potential of photodetectors for future wearable and foldable devices. This work demonstrates a heterogeneous, all‐carbon photodetector composed of graphene electrodes and porphyrin‐interfaced single‐walled CNTs (SWNTs) channel, exhibiting high photoresponse, flexibility, and full transparency across the device. The porphyrin molecules generate and transfer photoexcited holes to the SWNTs even under weak white light, resulting in significant improvement of photoresponsivity from negligible to 1.6 × 10^?2 A W^?1. Simultaneously, the photodetector exhibits high flexibility allowing stable light detection under ≈50% strain (i.e., a bending radius of ≈350 µm), and retaining a sufficient transparency of ≈80% at 550 nm. Experimental demonstrations as a wearable sunlight sensor highlight the utility of the photodetector that can be conformally mounted on human skin and other curved surfaces without any mechanical and optical constraints. The heterogeneous integration of porphyrin–SWNT–graphene may provide a viable route to produce invisible, high‐performance optoelectronic systems.     

Characteristics of carbon nanotubes grown by mesh-inserted plasma-enhanced chemical vapor deposition

Plasma-enhanced chemical vapor deposition (CVD) has the advantages of low temperature and vertical growth in synthesizing carbon nanotubes (CNTs), but has generally produced stubby CNTs, probably due to an ion bombardment effect. To suppress the ion bombardment, a metal mesh with the same electrical potential as that of the cathode was placed just above the substrate on the cathode. The anode was electrically grounded while the cathode and the mesh were both negatively biased, causing no plasma to occur below the mesh. The substrate was therefore separated from the plasma by the mesh so that the ion bombardment was suppressed. CNTs were grown on a 2 nm-thick Invar catalyst with different DC plasma powers of 0–112 W at 500 °C, 3.3 torr for 10 min, using C₂H₂ (28 sccm) and NH₃ (172 sccm). Compared to CNTs grown with no mesh, these CNTs showed smaller diameters and greater lengths. As the plasma power decreased, the CNTs grown with mesh were thinner and longer and resembled those grown at a higher temperature by thermal CVD. Etching these CNTs by N₂ plasma reduced their population density and considerably improved their field emission characteristics.     

Drop size distribution and holdup in a rotating impeller extraction column

A stagewise hydrodynamic model, applying drop population balance equations derived from models for breakage and coalescence of drops in a countercurrent liquid-liquid extraction system, was developed to predict the drop size distribution and the holdup of the dispersed phase in a rotating impeller extraction column. The drop size distributions were obtained by taking the photographs of the dispersions at the same locations through the rectangular shaped glass box filled with distilled water. The experimental variables were the impeller speed and flow rates of the continuous and dispersed phases. The solutions of the model equations were obtained by performing the computer simulation and the optimum parameter values were determined. The results predicted by the model were in good agreement with the experimental results obtained from the present rotating impeller extraction column.     

Blind digital watermarking of rational Bézier and B-spline curves and surfaces with robustness against affine transformations and Möbius reparameterization

We present a blind watermarking scheme for rational Bézier and B-spline curves and surfaces which is shape-preserving and robust against the affine transformations and Möbius reparameterization that are commonly used in geometric modeling operations in CAD systems. We construct a watermark polynomial with real coefficients of degree four which has the watermark as the cross-ratio of its complex roots. We then multiply the numerator and denominator of the original curve or surface by this polynomial, increasing its degree by four but preserving its shape. Subsequent affine transformations and Möbius reparameterization leave the cross-ratio of these roots unchanged. The watermark can be extracted by finding all the roots of the numerator and denominator of the curve or surface: the cross-ratio of the four common roots will be the watermark. Experimental results confirm both the shape-preserving property and its robustness against attacks by affine transformations and Möbius reparameterization.     

Direct analysis for the distribution of toxic glycoalkaloids in potato tuber tissue using matrix-assisted laser desorption/ionization mass spectrometric imaging

A simple and rapid analytical method for detection and spatial distribution of glycoalkaloids in potato tubers has been developed for the first time using matrix-assisted laser desorption/ionization mass spectrometric imaging (MALDI-MSI). For effective MALDI-MSI analysis, we have developed a uniform matrix coating method using 2,5-dihydroxybenzoic acid (2,5-DHB) as the preferred matrix which results in better sensitivity than 2,4,6-trihydroxyacetophenone (2,4,6-THAP) using MALDI-TOF. The relative concentrations of two major and two minor glycoalkaloids, α-chaconine and α-solanine, dehydrochaconine and dehydrosolanine, were clearly detected and distinguished in various parts of potato tuber and their relative amounts were directly compared. We also successfully showed the relative concentrations of glycoalkaloids that were accumulated by light exposure during storage using MALDI-MSI. Therefore, MALDI-MSI has been shown to be a useful technique for screening toxic and bioactive metabolites in foods and medicinal plants.     

Analysis for deformation behavior of multilayer ceramic capacitor based on multiscale homogenization approach

Given the rapid improvements in the miniaturization, functionality, and efficiency of electronic products in recent years, the dielectric layers and electrodes of multilayer ceramic capacitors have become thinner, with the number of stacked layers also increasing. As a result, the deformation defects induced during manufacturing of the capacitors have increased. In this study, the deformation behavior of a multilayer ceramic capacitor composed of ceramic dielectric layers and Ni electrode layers during the compression process was analyzed numerically using the FEM. To analyze the deformation behavior of the capacitor, which consisted of several hundred laminated ceramic and Ni layers, in the plane direction, the material properties were represented by equivalent material properties based on the multiscale homogenization approach. Then, the deformation of the capacitor in the plane direction owing to the residual stress arising during the compression process was analyzed based on the calculated equivalent material properties. Finally, the possibility of a product defect with the size of the ceramic dielectric and electrode layers during the cutting process was predicted.     

Design of a boil-off natural gas reliquefaction control system for LNG carriers

Onboard boil-off gas (BOG) reliquefaction is a new technology that liquefies BOG and returns it to the cargo tanks instead of burning it off during a voyage. For the commercial development of this technology, an object-oriented dynamic simulation is presented which facilitates the design of the plant and control system for the thermal process. A reliquefaction process based on the reverse Brayton cycle has been designed, and its static thermodynamic states at the design BOG load are presented. To make the cycle work for any BOG load, an idea was sought that would achieve a heat balance with the work extracted by the expander. Dynamic simulations were conducted for all operating modes, including start-up and idle. It was found that the expander exit temperature is the key process variable for control and that the process control works successfully when three actuators are activated in three different BOG load regimes. The study also shows that control of the separator pressure to keep the vapor fraction at the throttle valve exit as low as possible is an efficient method for purging nitrogen from BOG.     

Protective effects of chebulic acid from Terminalia chebula Retz. against t-BHP-induced oxidative stress by modulations of Nrf2 and its related enzymes in HepG2 cells

Food Science and Biotechnology - Although chebulic acid isolated from Terminalia chebular has diverse biological effects, its effects on the expression of nuclear factor erythroid 2-related factor...