Yttrium Doping Effects on Ferroelectricity and Electric Properties of As-Deposited Hf1-xZrxO2 Thin Films via Atomic Layer Deposition.

Hf1-xZrxO2 (HZO) thin films are versatile materials suitable for advanced ferroelectric semiconductor devices. Previous studies have shown that the ferroelectricity of HZO thin films can be stabilized by doping them with group III elements at low concentrations. While doping with Y improves the ferroelectric properties, there has been limited research on Y-HZO thin films fabricated using atomic layer deposition (ALD). In this study, we investigated the effects of Y-doping cycles on the ferroelectric and electrical properties of as-deposited Y-HZO thin films with varying compositions fabricated through ALD. The Y-HZO thin films were stably crystallized without the need for post-thermal treatment and exhibited transition behavior depending on the Y-doping cycle and initial composition ratio of the HZO thin films. These Y-HZO thin films offer several advantages, including enhanced dielectric constant, leakage current density, and improved endurance. Moreover, the optimized Y-doping cycle induced a phase transformation that resulted in Y-HZO thin films with improved ferroelectric properties, exhibiting stable behavior without fatigue for up to 1010 cycles. These as-deposited Y-HZO thin films show promise for applications in semiconductor devices that require high ferroelectric properties, excellent electrical properties, and reliable performance with a low thermal budget.

Preclinical mouse model of optical coherence tomography for subcortical brain imaging without dissection.

The purpose of this study was to investigate the feasibility of using optical coherence tomography (OCT) to identify internal brain lesions, specifically intracerebral hemorrhage, without dissection. Mice with artificially injected brain hematomas were used to test the OCT system, and the recorded images were compared with microscopic images of the same mouse brains after hematoxylin and eosin staining. The intracranial structures surrounding the hematomas were clearly visualized by the OCT system without dissection. These images reflect the ability of OCT to determine the extent of a lesion in several planes. OCT is a useful technology, and these findings could be used as a starting point for future research in intraoperative imaging.

A Sensor Fault-Tolerant Accident Diagnosis System.

Emergency situations in nuclear power plants are accompanied by an automatic reactor shutdown, which gives a big task burden to the plant operators under highly stressful conditions. Diagnosis of the occurred accident is an essential sequence for optimum mitigations; however, it is also a critical source of error because the results of accident identification determine the task flow connected to all subsequent tasks. To support accident identification in nuclear power plants, recurrent neural network (RNN)-based approaches have recently shown outstanding performances. Despite the achievements though, the robustness of RNN models is not promising because wrong inputs have been shown to degrade the performance of RNNs to a greater extent than other methods in some applications. In this research, an accident diagnosis system that is tolerant to sensor faults is developed based on an existing RNN model and tested with anticipated sensor errors. To find the optimum strategy to mitigate sensor error, Missforest, selected from among various imputation methods, and gated recurrent unit with decay (GRUD), developed for multivariate time series imputation based on the RNN model, are compared to examine the extent that they recover the diagnosis accuracies within a given threshold.

Consistency Index-Based Sensor Fault Detection System for Nuclear Power Plant Emergency Situations Using an LSTM Network.

A nuclear power plant (NPP) consists of an enormous number of components with complex interconnections. Various techniques to detect sensor errors have been developed to monitor the state of the sensors during normal NPP operation, but not for emergency situations. In an emergency situation with a reactor trip, all the plant parameters undergo drastic changes following the sudden decrease in core reactivity. In this paper, a machine learning model adopting a consistency index is suggested for sensor error detection during NPP emergency situations. The proposed consistency index refers to the soundness of the sensors based on their measurement accuracy. The application of consistency index labeling makes it possible to detect sensor error immediately and specify the particular sensor where the error occurred. From a compact nuclear simulator, selected plant parameters were extracted during typical emergency situations, and artificial sensor errors were injected into the raw data. The trained system successfully generated output that gave both sensor error states and error-free states.

Visualization of left ventricular Purkinje fiber distribution using widefield optical coherence microscopy.

BACKGROUND: The distribution and connection of ventricular Purkinje fibers are known to be associated with idiopathic left ventricular arrhythmias. Unusual anatomy is one of the important factors associated with catheter ablation success rate. With the widefield high-speed, swept-source optical coherence microscopy (OCM) and light microscope, we visualized the left ventricular Purkinje fiber distribution. METHODS: Left ventricular walls of five adult ovine hearts were incised from the mitral annulus to the apex. Using the widefield OCM technique and light microscopy, we observed the distribution, direction, depth, and dividing patterns of the Purkinje network with multiple tangential angles and without tissue destruction. RESULTS: Widefield OCM was used to characterize the ovine heart Purkinje network system in a 4 × 4 mm2 field. Left ventricular Purkinje fibers traveled in the sub-endocardial area near the left-sided peri-membranous septal area and ran like a wide hair bundle. The distal branching fibers penetrated to the endocardium and connected to the contractile muscle. In this distal area, Purkinje fibers were connected to each other, forming multiple layers. Some Purkinje fibers were directly connected within the false tendon between the papillary muscles or between the trabeculations. Some free-running Purkinje fibers were directly connected to the papillary muscle from the left bundle. CONCLUSION: Using widefield OCM, we were able to observe the left bundle and its branching patterns in ovine left ventricle without tissue destruction. This might be applied to future cardiac ablation procedures.

Combined Treatment with Low-Level Laser and rhBMP-2 Promotes Differentiation and Mineralization of Osteoblastic Cells under Hypoxic Stress.

BACKGROUND: The aim of this study was to evaluate the combined effect of low-level laser treatment (LLLT) and recombinant human bone morphological protein-2 (rhBMP-2) applied to hypoxic-cultured MC3T3-E1 osteoblastic cells and to determine possible signaling pathways underlying differentiation and mineralization of osteoblasts under hypoxia. METHODS: MC3T3-E1 cells were cultured under 1% oxygen tension for 72 h. Cell cultures were divided into four groups: normoxia control, low-level laser (LLL) alone, rhBMP-2 combined with LLLT, and rhBMP-2 under hypoxia. Laser irradiation was applied at 0, 24, and 48 h. Cells were treated with rhBMP-2 at 50 ng/mL. Alkaline phosphatase activity was measured at 3, 7, and 14 days to evaluate osteoblastic differentiation. Cell mineralization was determined with Alizarin red S staining at 7 and 14 days. Western blot assays were performed to evaluate whether p38/protein kinase D (PKD) signaling was involved. RESULTS: The results indicate that LLLT and rhBMP-2 synergistically increased alkaline phosphatase (ALP) activity and mineralization. Western blot analyses showed that expression of type I collagen, runt-related transcription factor 2 (RUNX2), and Osterix (Osx), increased and expression of hypoxia-inducible factor 1-alpha (HIF-1α), decreased more in the LLLT and rhBMP-2 combined group than in the rhBMP-2 or LLL alone groups. Moreover, LLLT and rhBMP-2 stimulated p38 phosphorylation and rhBMP-2 and LLLT increased Prkd1 phosphorylation. CONCLUSION: Combined treatment with rhBMP-2 and LLL induced differentiation and mineralization of hypoxic-cultured MC3T3-E1 osteoblasts by activating p38/PKD signaling in vitro.

A Hybrid Gate Dielectrics of Ion Gel with Ultra-Thin Passivation Layer for High-Performance Transistors Based on Two-Dimensional Semiconductor Channels.

We propose a hybrid gate structure for ion gel dielectrics using an ultra-thin Al2O3 passivation layer for realizing high-performance devices based on electric-double-layer capacitors. Electric-double-layer transistors can be applied to practical devices with flexibility and transparency as well as research on the fundamental physical properties of channel materials; however, they suffer from inherent unwanted leakage currents between electrodes, especially for channel materials with low off-currents. Therefore, the Al2O3 passivation layer was introduced between the metal electrodes and ion gel film as a leakage current barrier; this simple approach effectively reduced the leakage current without capacitance degradation. In addition, we confirmed that a monolayer MoS2 transistor fabricated with the proposed hybrid gate dielectric exhibited remarkably enhanced device properties compared to a transistor using a normal ion gel gate dielectric. Our findings on a simple method to improve the leakage current properties of ion gels could be applied extensively to realize high-performance electric-double-layer transistors utilizing various channel materials.

Chronic cocaine disrupts neurovascular networks and cerebral function: optical imaging studies in rodents.

Cocaine abuse can lead to cerebral strokes and hemorrhages secondary to cocaine's cerebrovascular effects, which are poorly understood. We assessed cocaine's effects on cerebrovascular anatomy and function in the somatosensory cortex of the rat's brain. Optical coherence tomography was used for in vivo imaging of three-dimensional cerebral blood flow (CBF) networks and to quantify CBF velocities (CBFv), and multiwavelength laser-speckle-imaging was used to simultaneously measure changes in CBFv, oxygenated (Δ[HbO2] ) and deoxygenated hemoglobin (Δ[HbR] ) concentrations prior to and after an acute cocaine challenge in chronically cocaine exposed rats. Immunofluorescence techniques on brain slices were used to quantify microvasculature density and levels of vascular endothelial growth factor (VEGF). After chronic cocaine (2 and 4 weeks), CBFv in small vessels decreased, whereas vasculature density and VEGF levels increased. Acute cocaine further reduced CBFv and decreased Δ[HbO2] and this decline was larger and longer lasting in 4 weeks than 2 weeks cocaine-exposed rats, which indicates that risk for ischemia is heightened during intoxication and that it increases with chronic exposures. These results provide evidence of cocaine-induced angiogenesis in cortex. The CBF reduction after chronic cocaine exposure, despite the increases in vessel density, indicate that angiogenesis was insufficient to compensate for cocaine-induced disruption of cerebrovascular function.

High speed image space parallel processing for computer-generated integral imaging system.

In an integral imaging display, the computer-generated integral imaging method has been widely used to create the elemental images from a given three-dimensional object data. Long processing time, however, has been problematic especially when the three-dimensional object data set or the number of the elemental lenses are large. In this paper, we propose an image space parallel processing method, which is implemented by using Open Computer Language (OpenCL) for rapid generation of the elemental images sets from large three-dimensional volume data. Using the proposed technique, it is possible to realize a real-time interactive integral imaging display system for 3D volume data constructed from computational tomography (CT) or magnetic resonance imaging (MRI) data.

Modulation of physical properties of polyvinylsiloxane impression materials by filler type combination.

Polyvinylsiloxanes (PVS), used as dental impression materials, were formulated with the variation of loading combination of six types of fillers including nano-sized fumed silica. The fillers were blended with three types of silicone polymers together with cross-linker and inhibitor in base paste and with plasticizer and platinum catalyst in catalyst paste. By replacing parts of crystalline quartz with other fillers, the setting time became much faster. The test group in which quarter of quartz was replaced with fumed silica showed the most ideal working and setting time for clinical use. There was a negative correlation between pH and setting time (p < 0.05). Combining the fumed silica was effective in increasing the viscosity, tensile strength and maximum% strain. Combining the diatomaceous earth reduced the setting time and maximum% strain, and dramatically increased the viscosity and tensile strength. The best modulation of physical properties of PVS material was possible by combining fillers during the formulation.