Resonator size effects on the TFBAR ladder filter performance

Thin-film bulk acoustic resonators with different resonator sizes are simulated and measured. Their effects on ladder filter performance are also presented. Aluminum nitride and platinum are used as piezoelectric material and electrodes, respectively. As the shunt resonator size increases, out-of-band rejection performance has been improved. The 3/2 stage filters that have twice or three times larger resonators reveal 6 dB and 11 dB out-of-band rejection improvements, respectively.     

A harmonic suppression antenna for an active integrated antenna

An inset-fed antenna with a shorting pin and slots is presented for harmonic suppression of an active integrated antenna. Its fundamental resonant frequency is 5.8 GHz. At fundamental and harmonic frequencies, return loss and radiation characteristics are measured and compared with those of the conventional microstrip patch antenna. The second and third harmonic return losses of the proposed antenna are suppressed to 6.7 dB and 17.7 dB with respect to the conventional patch antenna, respectively.     

Controlling Solvation and Solid-Electrolyte Interphase Formation to Enhance Lithium Interfacial Kinetics at Low Temperatures

Operation of lithium-based batteries at low temperatures (<0 °C) is challenging due to transport limitations as well as sluggish Li⁺ kinetics at the electrode interface. The complicated relationships among desolvation, charge transfer, and transport through the solid electrolyte interphase (SEI) at low temperatures are not well understood, hindering electrolyte development. Here, an ether/hydrofluoroether and fluoroethylene carbonate (FEC)-based ternary solvent electrolyte is developed to improve Li cycling at low temperatures (Coulombic efficiency of 93.3% at -40 °C), and the influence of the local solvation structure on interfacial Li⁺ kinetics and SEI chemistry is further revealed. The hydrofluoroether cosolvent allows for modulation of the solvation structure, thereby enabling facile Li⁺ desolvation while forming an inorganic-rich SEI, which are both beneficial for lowering Li⁺ kinetic barriers at the interface. This cosolvent also increases the oxidative stability of the electrolyte to over 4.0 V versus Li/Li⁺, thereby enabling cycling of NMC-based full cells at −40 °C. This study advances the understanding of the influence of Li⁺ solvation structure, SEI chemistry, and interfacial Li⁺ kinetics on Li electrochemistry at low temperatures, providing new design considerations for creating effective low-temperature electrolyte systems.     

Fabrication of high efficiency and color stable white organic light-emitting diodes by an alignment free mask patterning

Small molecule based white organic light-emitting diodes were fabricated by using an alignment free mask patterning method. A phosphorescent red/green emitting layer was patterned by a metal mask without any alignment and a blue phosphorescent emitting layer was commonly deposited on the patterned red/green emitting layer. A white emission could be obtained due to separate emission of red/green and blue emitting layers. A maximum current efficiency of 30.7 cd/A and a current efficiency of 26.0 cd/A at 1000 cd/m² were obtained with a color coordinate of (0.39, 0.45). In addition, there was little change of emission spectrum according to luminance because of balanced red/green and blue emissions.     

Controlling Electrostatic Interaction in PEDOT:PSS to Overcome Thermoelectric Tradeoff Relation

A high power factor must be achieved to improve the thermoelectric (TE) output of organic TE materials though the tradeoff between electrical conductivity and the Seebeck coefficient is a serious obstacle to the further development of these materials. Here, systematic control of the electrostatic interaction between a conducting polymer and a dopant induces a positive deviation from this TE tradeoff relation so that the electrical conductivity and the Seebeck coefficient simultaneously increase. Upon reduction of the electrostatic interaction, substantial changes in the film morphology, chain conformation, and crystalline ordering are observed, all of which critically affect the TE charge transport. As a result, the electrostatic interaction control is found to be an effective strategy to enhance the power factor, overcoming the tradeoff between TE parameters. Adapting this strategy to poly(3,4‐ethylenedioxythiophene):polystyrene‐sulfonate results in a remarkable power factor (=700.2 µW m^?1 K^?2 ) and figure of merit ZT (=0.25).     

Usefulness of CT in patients with intestinal obstruction who have undergone abdominal surgery for malignancy

OBJECTIVE: The purpose of this study was to evaluate the usefulness of CT in determining the causes of intestinal obstruction in patients who have undergone abdominal surgery for malignancy. MATERIALS AND METHODS: We analyzed the CT scans of 55 patients with benign (n = 26) or malignant (n = 29) intestinal obstruction that developed after abdominal surgery for malignancy. After calculating the diagnostic accuracy of interpretations by three radiologists, we compared CT findings for benign and malignant intestinal obstructions with respect to peritoneal involvement patterns and other ancillary findings. Multivariate logistic regression analysis was used to determine the diagnostic performance of CT in revealing causes of obstruction. RESULTS: Diagnostic accuracies of the three radiologists were 67%, 75%, and 78%. CT findings indicating malignant obstruction were a mass at the site of obstruction or prior surgery, lymphadenopathy, or an abrupt transition zone and irregular bowel wall thickening at obstructed sites (p < .05). Conversely, the chance for benign obstruction increased when CT revealed mesenteric vascular changes, a large amount of ascites, or a smooth transition zone and smooth bowel wall thickening at the obstructed site (p < .05). With multivariate logistic regression analysis using two variables (a mass at the site of obstruction or prior surgery and lymphadenopathy), we calculated the overall accuracy of CT as 84% (46/55 patients). CONCLUSION: CT is useful in differentiating benign from malignant intestinal obstructions in patients who have undergone abdominal surgery for malignancy. However, CT has limitations in patients not having a demonstrable peritoneal mass.     

Bistability and improved hole injection in organic bistable light-emitting diodes using a quantum dot embedded hole transport layer

Organic bistable light-emitting diodes (OBLED) were developed by using a quantum dot embedded hole transport layer in the organic light-emitting diodes. The driving voltage of the OBLED was decreased due to the good hole transport properties of quantum dot embedded hole transport layer and the OBLED also showed bistability at negative bias due to the switching behavior of the quantum dot based hole transport layer. The origin for the switching behavior of the OBLED was confirmed by fabricating organic bistable device with the quantum dot embedded hole transport layer.     

Organic Materials for Deep Blue Phosphorescent Organic Light‐Emitting Diodes

Recently, great progress has been made in the device performance of deep blue phosphorescent organic light‐emitting diodes (PHOLEDs) by developing high triplet energy charge‐transport materials, high triplet energy host and deep blue emitting phosphorescent dopant materials. A high quantum efficiency of over 25% and a high power efficiency of over 15 lm/W have already been achieved at 1000 cd m^?2 in the deep blue PHOLEDs with a y color coordinate less than 0.20. In this work, recent developments in organic materials for high efficiency deep blue PHOLEDs are reviewed and a future strategy for the development of high efficiency deep blue PHOLEDs is proposed.     

Robust and multifunctional nanosheath for chemical and biological nanodevices

The contribution of advanced nanoscale chemical and biological devices to life science has been limited to a small number of nanomaterials, due to the absence of effective surface modification routes. Herein, we demonstrate a polymer-like nanosheath synthesized by nonthermal plasma technology (NPT) that can protect the core nanomaterial from the solution environment and provide a multifunctional platform for chemical and biological nanosensors. For ZnO nanowires (NWs) which are unstable in solution, we demonstrate that this nanosheath makes it possible for ZnO NW field-effect transistors to act as a pH sensor for 24 h and a biosensor for the real-time, label-free detection of liver cancer markers.