Effects of Electrode Thickness on Three-Dimensional NiCrAl Metal Foam Cathode for Lithium Ion Battery.

LiFePO4 electrodes using three dimensional NiCrAl alloy metal foam of different electrode thickness are prepared. In order to improve the electrochemical and cycle-life performance of lithium ion batteries, it is important to optimize the electrode thickness and mass loading of active material. As compared to those with thick electrode, the cells with thin electrode exhibit high rate performance and cycle-life behavior, due to the shorter diffusion length of lithium-ion and improved kinetic behavior. Also, cyclic voltammetry curves and electrochemical impedance spectroscopy analysis indicate that the redox reaction for the thinner electrode occurs much faster, and the charge transfer resistance is much lower. The results of same current density (mA cm-2) show that 450 µm-thickness electrode exhibits superior electrochemical and power performance. It is because the 300 µm-thickness electrode which has the lowest mass loading of active material meant that it carried the highest current rate, and thicker electrodes show higher internal resistance and much poorer kinetic property. Namely, electrode thickness and an amount of active material are difference according to the intended use.

Solvent and Intermediate Phase as Boosters for the Perovskite Transformation and Solar Cell Performance.

High power conversion efficiency and device stabilization are two major challenges for CH3NH3PbI3 (MAPbI3) perovskite solar cells to be commercialized. Herein, we demonstrate a diffusion-engineered perovskite synthesis method using MAI/ethanol dipping, and compared it to the conventional synthesis method from MAI/iso-propanol. Diffusion of MAI/C2H5OH into the PbCl2 film was observed to be more favorable than that of MAI/C3H7OH. Facile perovskite conversion from ethanol and highly-crystalline MAPbI3 with minimized impurities boosted the efficiency from 5.86% to 9.51%. Additionally, we further identified the intermediates and thereby the reaction mechanisms of PbCl2 converting into MAPbI3. Through straightforward engineering to enhance the surface morphology as well as the crystallinity of the perovskite with even faster conversion, an initial power conversion efficiency of 11.23% was obtained, in addition to superior stability after 30 days under an ambient condition.

Sub-kT/q Subthreshold-Slope Using Negative Capacitance in Low-Temperature Polycrystalline-Silicon Thin-Film Transistor.

Realizing a low-temperature polycrystalline-silicon (LTPS) thin-film transistor (TFT) with sub-kT/q subthreshold slope (SS) is significantly important to the development of next generation active-matrix organic-light emitting diode displays. This is the first time a sub-kT/q SS (31.44 mV/dec) incorporated with a LTPS-TFT with polycrystalline-Pb(Zr,Ti)O3 (PZT)/ZrTiO4 (ZTO) gate dielectrics has been demonstrated. The sub-kT/q SS was observed in the weak inversion region at -0.5 V showing ultra-low operating voltage with the highest mobility (250.5 cm(2)/Vsec) reported so far. In addition, the reliability of DC negative bias stress, hot carrier stress and self-heating stress in LTPS-TFT with negative capacitance was investigated for the first time. It was found that the self-heating stress showed accelerated SS degradation due to the PZT Curie temperature.

Integrating Epitaxial-Like Pb(Zr,Ti)O3 Thin-Film into Silicon for Next-Generation Ferroelectric Field-Effect Transistor.

The development of ferroelectric random-access memory (FeRAM) technology with control of grain boundaries would result in a breakthrough for new nonvolatile memory devices. The excellent piezoelectric and electrical properties of bulk ferroelectrics are degraded when the ferroelectric is processed into thin films because the grain boundaries then form randomly. Controlling the nature of nucleation and growth are the keys to achieving a good crystalline thin-film. However, the sought after high-quality ferroelectric thin-film has so far been thought to be impossible to make, and research has been restricted to atomic-layer deposition which is extremely expensive and has poor reproducibility. Here we demonstrate a novel epitaxial-like growth technique to achieve extremely uniform and large rectangular-shaped grains in thin-film ferroelectrics by dividing the nucleation and growth phases. With this technique, it is possible to achieve 100-µm large uniform grains, even made available on Si, which is large enough to fabricate a field-effect transistor in each grain. The electrical and reliability test results, including endurance and retention test results, were superior to other FeRAMs reported so far and thus the results presented here constitute the first step toward the development of FeRAM using epitaxial-like ferroelectric thin-films.

Comparison of RECIST version 1.0 and 1.1 in assessment of tumor response by computed tomography in advanced gastric cancer.

OBJECTIVE: Response Evaluation Criteria in Solid Tumors (RECIST) guideline version 1.0 (RECIST 1.0) was proposed as a new guideline for evaluating tumor response and has been widely accepted as a standardized measure. With a number of issues being raised on RECIST 1.0, however, a revised RECIST guideline version 1.1 (RECIST 1.1) was proposed by the RECIST Working Group in 2009. This study was conducted to compare CT tumor response based on RECIST 1.1 vs. RECIST 1.0 in patients with advanced gastric cancer (AGC). METHODS: We reviewed 61 AGC patients with measurable diseases by RECIST 1.0 who were enrolled in other clinical trials between 2008 and 2010. These patients were retrospectively re-analyzed to determine the concordance between the two response criteria using the κ statistic. RESULTS: The number and sum of tumor diameters of the target lesions by RECIST 1.1 were significantly lower than those by RECIST 1.0 (P<0.0001). However, there was excellent agreement in tumor response between RECIST 1.1 and RECIST 1.0 (κ=0.844). The overall response rates (ORRs) according to RECIST 1.0 and RECIST 1.1 were 32.7% (20/61) and 34.5% (20/58), respectively. One patient with partial response (PR) based on RECIST 1.0 was reclassified as stable disease (SD) by RECIST 1.1. Of two patients with SD by RECIST 1.0, one was downgraded to progressive disease and the other was upgraded to PR by RECIST 1.1. CONCLUSIONS: RECIST 1.1 provided almost perfect agreement with RECIST 1.0 in the CT assessment of tumor response of AGC.

Left transradial coronary angiography in a patient with dextrocardia.

Although dextrocardia occurs rarely, the incidence of coronary artery disease is similar to the general population. Because of unfamiliarity with performing catheterization, transradial coronary angiography has seldom been performed in a patient with dextrocardia. We successfully performed left transradial coronary angiography in a patient with a right side heart using counter-directional torquing of the catheters and mirror-image angiographic angles.