RESUMEN
Recently, there have been various attempts to demonstrate the feasibility of transition metal dichalcogenide (TMD) transistors for digital logic circuits. A complementary inverter circuit, which is a basic building block of a logic circuit, was implemented in earlier works by heterogeneously integrating n- and p-channel transistors fabricated on different TMD materials. Subsequently, to simplify the circuit design and fabrication process, complementary inverters were constructed on single-TMD materials using ambipolar transistors. However, continuous transition from the electron-conduction to the hole-conduction state in the ambipolar devices led to the problem of a high leakage current. Here, we report a polarity-controllable TMD transistor that can operate as both an n- and a p-channel transistor with a low leakage current of a few picoamperes. The device polarity can be switched simply by converting the sign of the drain voltage. This is because a metal-like tungsten ditelluride (WTe2) with a low carrier concentration is used as a drain contact, which subsequently allows selective carrier injection at the palladium/tungsten diselenide (WSe2) junction. In addition, by using the operating principle of the polarity-controllable transistor, we demonstrate a complementary inverter circuit on a single TMD channel material (WSe2), which exhibits a very low static power consumption of a few hundred picowatts. Finally, we confirm the expandability of this polarity-controllable transistor toward more complex logic circuits by presenting the proper operation of a three-stage ring oscillator.
RESUMEN
Objective: The purpose of this study was to compare the efficacy and complications between cesarean hysterectomy and uterine artery embolization (UAE) in the management of postpartum bleeding.Material and methods: We analyzed the outcomes of 48 patients who underwent cesarean hysterectomy from October 2007 to January 2017, and 333 patients who underwent UAE for postpartum bleeding which was unresponsive to conservative management. We reviewed all medical records retrospectively, and assessed the length of hospital stay, amount of blood transfused, operative time, and all procedural-related complications.Results: There was a significant difference between the two groups in the mean hospital stay between the cesarean hysterectomy group and the UAE group (12.88 ± 15.37 days vs. 7.37 ± 15.92 days, respectively). The number of transfusions received by those in the cesarean hysterectomy group was larger than that in the UAE group, and this difference was also statistically significant (16.81 ± 11.23 pints vs. 5.59 ± 7.02 pints). The mean operative time of the UAE procedure was significantly shorter than the cesarean hysterectomy procedure (83 min vs. 179 min, respectively). We also closely compared complications during and after the procedures.Conclusion: We concluded that UAE is safer and more effective than cesarean hysterectomy for the management of postpartum hemorrhage unresponsive to conservative management.