Sub-Nanosecond Switching of Si:HfO2 Ferroelectric Field-Effect Transistor

The discovery of ferroelectric doped HfO₂ enabled the emergence of scalable and CMOS-compatible ferroelectric field-effect transistor (FeFET) technology which has the potential to meet the growing need for fast, low-power, low-cost, and high-density nonvolatile memory, and neuromorphic devices. Although HfO₂ FeFETs have been widely studied in the past few years, their fundamental switching speed is yet to be explored. Importantly, the shortest polarization time demonstrated to date in HfO₂-based FeFET was ∼10 ns. Here, we report that a single subnanosecond pulse can fully switch HfO₂-based FeFET. We also study the polarization switching kinetics across 11 orders of magnitude in time (300 ps to 8 s) and find a remarkably steep time-voltage relation, which is captured by the classical nucleation theory across this wide range of pulse widths. These results demonstrate the high-speed capabilities of FeFETs and help better understand their fundamental polarization switching speed limits and switching kinetics.

Reconfigurable Low-Voltage Hexagonal Boron Nitride Nonvolatile Switches for Millimeter-Wave Wireless Communications

Recently, nonvolatile resistive switching memory effects have been actively studied in two-dimensional (2D) transition metal dichalcogenides and boron nitrides to advance future memory and neuromorphic computing applications. Here, we report on radiofrequency (RF) switches utilizing hexagonal boron nitride (h-BN) memristors that afford operation in the millimeter-wave (mmWave) range. Notably, silver (Ag) electrodes to h-BN offer outstanding nonvolatile bipolar resistive switching characteristics with a high ON/OFF switching ratio of 10¹¹ and low switching voltage below 0.34 V. In addition, the switch exhibits a low insertion loss of 0.50 dB and high isolation of 23 dB across the D-band spectrum (110 to 170 GHz). Furthermore, the S₂₁ insertion loss can be tuned through five orders of current compliance magnitude, which increases the application prospects for atomic switches. These results can enable the switch to become a key component for future reconfigurable wireless and 6G communication systems.

Risk factors associated with candidaemia in the neonatal intensive care unit: a case–control study

The incidence of candidaemia is steadily increasing in neonatal intensive care units (NICUs). Several neonatal risk factors for candidaemia have been identified, however, the number of cases in controlled studies is small and knowledge concerning maternal and perinatal risk factors is limited. The present study attempted to identify modifiable, independent maternal, perinatal and neonatal risk factors for candidaemia using a retrospective case-control study in the NICU of a tertiary-care paediatric medical centre. The study group consisted of 56 neonates admitted to the NICU between 1996 and 2000 who acquired candidaemia. The control group comprised the first infant admitted immediately after each study infant matched for gestational age (+/-10 days) and birthweight (+/-200 g). Potential maternal, perinatal and neonatal risk factors were compared between the groups using statistical methods and analysed by univariate and multivariate stepwise logistic regression models. The independent risk factors found to be significantly associated with increased risk of candidaemia were duration of ventilation and presence of bacteraemia before candidaemia. Maternal steroids had a significant protective effect. The positive predictive value using these three parameters was 78.38%. Maximizing in-utero steroid treatment in high-risk pregnancies, minimizing the days of mechanical ventilation and investment of efforts in prevention of bacteraemia may help to reduce the incidence of candidaemia in the NICU.

Isolated fetal ascites caused by Wolman disease

Wolman disease is a rare autosomal-recessive disorder caused by reduced levels of lysosomal acid lipase. It occurs in infancy and is fatal in most cases before the age of 1 year. Affected infants show signs of lipid storage in most tissues, including hepatosplenomegaly, abdominal distension, vomiting, steatorrhea, failure to thrive, and adrenal calcifications. We present a case of isolated fetal ascites diagnosed at 32 weeks of gestation, with negative work-up for immune and non-immune hydrops fetalis and congenital infections and malformations. After delivery, the diagnosis of Wolman disease was established. Although rare, storage diseases such as Wolman disease should be considered in cases of isolated fetal ascites.