Electromagnetically induced transparency (EIT) analogs using metamaterials have diverse applications, including nonlinear optics, telecommunications, and biochemical sensors. These EIT analogs can be ...actively controlled by embedding semiconducting materials into metamaterial structures, but most active EIT metamaterials require complex optical setups and complicated fabrication processes. Graphene‐based EIT metamaterials are some of the most promising active EIT systems because of their simple controllability by electrical bias, but related researches have so far been limited to theoretical or numerical studies. Here, experimentally verified graphene EIT metamaterials are provided by controlling the terahertz funneling of the unique metaatom structures. The proposed active EIT metamaterials are fabricated on flexible and ultrathin polyimide films to acquire the lowest substrate insertion losses and achieve a 1 ps group delay change at the transmission peak of the EIT analog. Moreover, because the proposed metamaterials exhibit resonance properties that vary depending on the polarization direction, the phase delay can be controlled up to 80° from the proposed metamaterials by rotating the incident polarization to the orthogonal direction. Overall, by controlling the group and phase delay of incident waves in a single metamaterial device simultaneously, a multifunctional active tuning system can be realized in the terahertz range.
Both group delay and phase control of terahertz waves are realized in a single device by controlling graphene‐based anisotropic metamaterials. For specific polarization, an electromagnetically induced transparency analog can be controlled by manipulating the terahertz funneling in active metamaterials, whereas the phase property can be changed by controlling the interconnection between metaatoms for orthogonal polarization.
Electroluminescence from quantum dots (QDs) is a suitable photon source for futuristic displays offering hyper‐realistic images with free‐form factors. Accordingly, a nondestructive and scalable ...process capable of rendering multicolored QD patterns on a scale of several micrometers needs to be established. Here, nondestructive direct photopatterning for heavy‐metal‐free QDs is reported using branched light‐driven ligand crosslinkers (LiXers) containing multiple azide units. The branched LiXers effectively interlock QD films via photo‐crosslinking native aliphatic QD surface ligands without compromising the intrinsic optoelectronic properties of QDs. Using branched LiXers with six sterically engineered azide units, RGB QD patterns are achieved on the micrometer scale. The photo‐crosslinking process does not affect the photoluminescence and electroluminescence characteristics of QDs and extends the device lifetime. This nondestructive method can be readily adapted to industrial processes and make an immediate impact on display technologies, as it uses widely available photolithography facilities and high‐quality heavy‐metal‐free QDs with aliphatic ligands.
Nondestructive direct photopatterning for heavy‐metal‐free quantum dots is presented by using branched light‐driven ligand crosslinkers containing multiple azide units. The branched crosslinkers effectively interlock quantum dot films without compromising the intrinsic photoluminescence and electroluminescence properties of quantum dots. This nondestructive method can be directly adapted to photolithography facilities widely available in industry.
Active control of metamaterial properties is critical for advanced terahertz (THz) applications. However, the tunability of THz properties, such as the resonance frequency and phase of the wave, ...remains challenging. Here, a new device design is provided for extensively tuning the resonance properties of THz metamaterials. Unlike previous approaches, the design is intended to control the electrical interconnections between the metallic unit structures of metamaterials. This strategy is referred to as the molecularization of the meta‐atoms and is accomplished by placing graphene bridges between the metallic unit structures whose conductivity is modulated by an electrolyte gating. Because of the scalable nature of the molecularization, the resonance frequency of the terahertz metamaterials can be tuned as a function of the number of meta‐atoms constituting a unit metamolecule. At the same time, the voltage‐controlled molecularization allows delicate control over the phase shift of the transmitted THz, without changing the high transmission of the materials significantly.
A new device design for extensively tuning terahertz (THz) metamaterial resonances is realized by controlling the electrical interconnection between meta‐atoms. This strategy is referred to as the molecularization of the meta‐atoms and allows delicate control of the resonance frequency and phase shift of the transmitted THz waves by using graphene and ion‐gel gating system on flexible thin‐film substrates.
The charge carrier density of copper sulfide nanocrystals (Cu2−xS NCs) is sensitive to variations in the atomic composition, which determines the nature of sulfur bonding (sulfur-to-sulfur bonding or ...copper-to-sulfur bonding) in the lattice. Therefore, the fine control of the composition of Cu2−xS NCs, particularly in thin-film assemblies, provides a versatile strategy for tuning the electronic properties of materials that can be directly applied in electronic devices. Herein, we report that the atomic composition of the Cu2−xS NC assemblies (x = 0.9; cation/anion ratio = 1.1/1) can be controlled by introducing monovalent lithium ions into the assemblies (yielding Li0.7Cu2−xS NCs; x = 0.9; cation/anion ratio = 1.8/1) and reversibly extracting these cations from the assemblies through electrochemical methods. The electrochemically controlled uptake and release of lithium ions in Cu2−xS NC assemblies enabled the systematic tuning of the characteristic near-infrared absorbance (NIR) of the thin-film assemblies based on the localized surface plasmon resonance; NIR absorbance at 1300 nm wavelength, for example, could be controlled by more than 75% by exploiting the reversible doping process.
The decellularization and recellularization is a promising approach for tissue engineering and regenerative medicine. However, the decellularization process depletes important components like ...glycosaminoglycans (GAGs), affecting cell attachment and causing immunogenicity. Studies have explored various surface modification strategies to enhance recellularization.
To optimize the decellularization method, we employed whole kidney perfusion and slice kidney immersion/agitation techniques. The decellularized extracellular matrix (dECM) was then analyzed using hematoxylin and eosin (H&E) staining, scanning electron microscope (SEM), and DNA quantification. To enhance cell proliferation efficiency, albumin coating and rotating culture were applied. Also, we evaluated in vitro blood clot formation on the albumin-coated dECM by immersing it in blood.
After decellularization, the unique structures of the kidney were preserved whether cellular components were removed. Subsequently, we utilized albumin coating and rotating culture for recellularization, and observed that albumin-coated dECM not only promoted high cell proliferation rates but also prevented blood clot formation.
The albumin-coated dECM promoted cell proliferation and reduced blood clot formation in vitro. Also, dynamic culture condition using rotating culture allowed for improved cellular penetration into the dECM, leading to a conductive environment for enhanced tissue infiltration. This new approach suggests that the combined utilization of albumin coating and rotating culture conditions can improve the efficiency of recellularization.
The porcine kidneys were sliced and decellularized. After decellularization, the dECM was coated with albumin to enhance cell adhesion and promote cell proliferation. Additionally, the use of rotating culture increased tissue penetration of cells and improved the efficiency of recellularization. Display omitted
An analytical model for the bulk trap charge-induced threshold voltage variation in the intrinsic channel MOSFET is presented. A new definition of the flat band voltage, the gate voltage necessary to ...nullify the gate charge, which is induced by the bulk charges, is introduced. With the newly defined flat band voltage based on the bulk charge sheet approximation, the analytical MOS equations are derived for both the intrinsic channel nanowire and planar MOSFETs. It is shown that the analytical models predict the device characteristics reasonably well, compared with the numerical device simulations. Also, the error induced by the charge sheet approximation is compared with the point charge, using the numerical simulation. The model will be useful to predict the threshold voltage variation of the intrinsic poly-Si, adopted by the modern 3-D nand flash memory cell transistors.
White light is attained by combining different‐colored emissions. White organic light‐emitting diodes, therefore, should be fabricated to obtain mixed emissions from different organic luminophores ...while suppressing energy transfer between each other. Here, the authors present a simple means to realize this goal by forming two‐color strip‐patterns of light‐emitting polymer (orange) and an iridium complex (sky‐blue) luminophores entirely through solution processes. The formation of the two‐color patterns is facilitated by i) the use of a highly efficient crosslinker permitting the construction of structurally robust orange primary strip‐patterns and ii) the contrast in the surface energy allowing selective wetting of the secondary sky‐blue patterns between the orange primary patterns. The emissive layer comprising the two‐color strip ‐patterns allows for the mixing ratio of the two colors to be adjusted by simply varying the areal ratio of the two patterns, which in turn, controls the white emission color‐temperature from 2119 to 7994 K.
White organic light‐emitting diodes with two‐color strip‐patterns are fabricated through solution processes. The formation of the two‐color patterns is facilitated using the crosslinkers permitting the construction of orange strip patterns and the contrast in the surface energy allowing selective wetting of the sky‐blue patterns. Warm‐to‐cold white light control is realized by varying the areal ratio of the two‐color strip‐patterns.
A light‐emitting electrochemical cell (LEC) is an innovative device with a simple structure wherein a mixture of a luminophore and an electrolyte is sandwiched between electrodes. Here, LECs are ...presented which contain an active layer composed of green‐emitting InP/ZnSeS quantum dots (QDs) blended with polyvinyl carbozole p‐type polymer semiconductors and 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid (IL). The blending of QDs with polymer semiconductors increases the density of holes reaching the QDs; this, in turn, leads to luminescence from QDs, which is unachievable without the presence of polyvinyl carbazole semiconductor. Moreover, the deposition of a zinc oxide nanoparticle layer onto the QD–polymer–IL active layer increases the density of electrons reaching the QDs. The composition of these materials is varied systematically for balancing the injection rates of electron versus hole into the QDs. A luminance of ≈632 cd m−2 and an efficiency of >1.3 cd A−1 are achieved.
Light‐emitting electrochemical cells employing InP quantum dots (QDs) are reported for the first time. Based on systematic approach to balance the injection of electrons and holes into the QDs, a luminescence of ≈632 cd m−2 and an efficiency of >1.3 cd A−1 are achieved.
In article number 1802760, Moon Sung Kang, Hojin Lee, and co‐workers present a new device design for extensively tuning the terahertz metamaterial resonances by controlling the electrical ...interconnection between meta‐atoms. This strategy is referred to as the molecularization of the meta‐atoms and allows delicate control of the resonance frequency and phase shift of the transmitted THz waves by using graphene and an ion‐gel gating system on flexible thin‐film substrates.
Recently, the field of regenerative medicine has made great strides in the development of new treatments for various organ dysfunctions. One of the most promising new approaches is the use of ...three‐dimensional (3D) printing and autologous tissues. In this study, we evaluated the safety of a 3D‐printed autologous omentum patch to kidneys using large animals. A total of seven micropigs underwent transplantation of the 3D‐printed autologous omentum patch. Twelve weeks after transplantation, the safety was evaluated by measuring body weight, blood, and the renal resistive index. In addition, biopsy samples were histologically analyzed. The results showed no surgical complications, renal functional hematological changes, or inflammatory responses. Therefore, this study provides important insights into direct therapy to kidneys with a 3D‐printed patch made of autologous tissue. Furthermore, it has the potential for the development of new therapies for various organ dysfunction.
PDF
