Approaching the Ideal Linearity in Epitaxial Crystalline-Type Memristor by Controlling Filament Growth.

Brain-inspired neuromorphic computing has attracted widespread attention owing to its ability to perform parallel and energy-efficient computation. However, the synaptic weight of amorphous/polycrystalline oxide based memristor usually exhibits large nonlinear behavior with high asymmetry, which aggravates the complexity of peripheral circuit system. Controllable growth of conductive filaments is highly demanded for achieving the highly linear conductance modulation. However, the stochastic behavior of the filament growth in commonly used amorphous/polycrystalline oxide memristor makes it very challenging. Here, the epitaxially grown Hf0.5Zr0.5O2-based memristor with the linearity and symmetry approaching ideal case is reported. A layer of Cu nanoparticles is inserted into epitaxially grown Hf0.5Zr0.5O2 film to form the grain boundaries due to the breaking of the epitaxial growth. By combining with the local electric field enhancement, the growth of filament is confined in the grain boundaries due to the fact that the diffusion of oxygen vacancy in crystalline lattice is more difficult than that in the grain boundaries. Furthermore, the decimal operation and high-accuracy neural network are demonstrated by utilizing the highly linear and multi-level conductance modulation capacity. This method opens an avenue to control the filament growth for the application of resistance random access memory (RRAM) and neuromorphic computing.

Highly Energy-Efficient Spin Current Generation in SrIrO3 by Manipulating the Octahedral Rotation.

Materials with strong spin-orbit coupling (SOC) have been continuously attracting intensive attention due to their promising application in energy-efficient, high-density, and nonvolatile spintronic devices. Particularly, transition-metal perovskite oxides with strong SOC have been demonstrated to exhibit efficient charge-spin interconversion. In this study, we systematically investigated the impact of epitaxial strain on the spin-orbit torque (SOT) efficiency in the SrIrO3(SIO)/Ni81Fe19(Py) bilayer. The results reveal that the SOT efficiency is strongly related to the octahedral rotation around the in-plane axes of the single-crystal SIO. By modulating the epitaxial strain using different substrates, the SOT efficiency can be remarkably improved from 0.15 to 1.45. This 10-fold enhancement of SOT efficiency suggests that modulating the epitaxial strain is an efficient approach to control the SOT efficiency in complex oxide-based heterostructures. Our work may have the potential to advance the application of complex oxides in energy-efficient spintronic devices.

Interface-engineered ferroelectricity of epitaxial Hf0.5Zr0.5O2 thin films.

Ferroelectric hafnia-based thin films have attracted intense attention due to their compatibility with complementary metal-oxide-semiconductor technology. However, the ferroelectric orthorhombic phase is thermodynamically metastable. Various efforts have been made to stabilize the ferroelectric orthorhombic phase of hafnia-based films such as controlling the growth kinetics and mechanical confinement. Here, we demonstrate a key interface engineering strategy to stabilize and enhance the ferroelectric orthorhombic phase of the Hf0.5Zr0.5O2 thin film by deliberately controlling the termination of the bottom La0.67Sr0.33MnO3 layer. We find that the Hf0.5Zr0.5O2 films on the MnO2-terminated La0.67Sr0.33MnO3 have more ferroelectric orthorhombic phase than those on the LaSrO-terminated La0.67Sr0.33MnO3, while with no wake-up effect. Even though the Hf0.5Zr0.5O2 thickness is as thin as 1.5 nm, the clear ferroelectric orthorhombic (111) orientation is observed on the MnO2 termination. Our transmission electron microscopy characterization and theoretical modelling reveal that reconstruction at the Hf0.5Zr0.5O2/ La0.67Sr0.33MnO3 interface and hole doping of the Hf0.5Zr0.5O2 layer resulting from the MnO2 interface termination are responsible for the stabilization of the metastable ferroelectric phase of Hf0.5Zr0.5O2. We anticipate that these results will inspire further studies of interface-engineered hafnia-based systems.

[Pathologic observation on animal model of silicosis].

OBJECTIVE: To explore the pathological changes of pulmonary fibrosis induced by SiO2 in rats and pigs. METHODS: The silicosis models in rats and pigs were established by non-exposure method. The pathologic changes in lung tissues of rats and pigs were observed with HE staining under a light microscopy and under a transmission electron microscopy (TEM), the expression of cytokines was detected by immunohistochemistry. RESULTS: (1) The main pathologic changes of silicosis models in rats and pigs included: in 7 ∼ 15 days after treatment, silica dusts, dust cells, a lot of macrophages, lung epithelial cells, a few neutrophils, macrophage alveolar inflammation and nodules of stage I were found in alveolar space; in 30 ∼ 90 days after treatment, many nodules of stage I-III or IV with lymphocytes infiltration were observed in respiratory bronchioles, alveoli, interlobular septa, the subpleural and around blood vessels and bronchi. (2) The expression levels of CK protein, SP-A protein, CD68, b-FGF, TNF-α, IL-6, TGF-ß1, NFKappa/P50, Kappa/P65 and VEGF reduced with exposure time, but still were higher than those of the control. (3) The shed alveolar type I cells, proliferation of alveolar type II cells or macrophages and activated cellular function induced by silica were observed under TEM. CONCLUSION: The development of pulmonary fibrosis in silicosis models corresponded with the process from macrophages alveolar inflammation to pulmonary fibrosis.

[Diagnostic value and clinical application of CT/HRCT for coal workers' pneumoconiosis with large opacities].

OBJECTIVE: To study the diagnostic value of CT/HRCT for the coal workers' pneumoconiosis (CWP) with large opacities. METHODS: Sixty-two patients with CWP were examined with both chest radiograph and CT/HRCT scan. Comparison was done. RESULTS: Large opacities were found in 19 patients in the chest radiograph of 62 patients with CWP. The detection rate was 30.6%. Thirty large opacities were found using chest radiograph. Forty-three patients with large opacities were found using the CT/HRCT. The detection rate was 69.4%. One hundred and twenty-three large opacities were found using CT/HRCT. Ninety-three more large opacities were found by CT/HRCT than by chest radiograph. The total detection rate of large opacities by CT was 4.1 times than by chest radiograph. Both differences were statistically significant (chi2 = 18.58, P < 0.01). CT/HRCT found all patients with large opacities detected in the chest radiograph. Seventeen patients with Stage III large opacities (>or= 1.0 cm x 2.0 cm) were found by the chest radiograph. The detection rate was 27.4% (17/62). Twenty-seven large opacities were found using chest radiograph. Thirty-four patients with Stage III large opacities were found using the CT/HRCT. The detection rate was 54.8%. The found Stage III large opacities added up to 67. The found Stage III large opacities by CT/HRCT were 40 more than using chest radiograph. Both differences were statistically significant (chi2 = 9.63, P < 0.01). CT/HRCT was reliable to show the morphology, the inside structure, the tiny lesion and the special location of the large opacities of CWP. It could provide more important information for differential diagnosis. CONCLUSION: CT/HRCT is significantly better than the chest radiograph in the diagnosis of complicated CWP. It can find the large opacities that the chest radiograph can not. It has a great diagnostic and practical value as an assistant examination method. CT/HRCT could be considered as the reference and evidence for staging progression in diagnosis of pneumoconiosis.

[The diagnostic value and morphologic manifestation of high resolution computerized tomography in coal miner's pneumoconiosis with pleural pathological changes].

OBJECTIVE: To analyse CT and high resolution computerized tomography (HRCT) diagnostic value and morphologic manifestation in coal miner's pneumoconiosis with pleural pathological changes. METHODS: One hundred and thirty-one cases of coal miner patients with pneumoconiosis (0(+) type: 14 cases, type I: 46 cases, type II: 58 cases, type III: 13 cases) and 20 normal people as control group were first examined by routine CT scan at 4 fixed slices, followed by HRCT examination at the region of interest (ROI). Meanwhile, all of them had high-kV chest radiography. RESULTS: According to the national standard of the People's Republic of China in the diagnosis of coal miner's pneumoconiosis with pleural plaque, 68 cases of pleural disease making up 51.91% (68/131) were found (type I accounted for 17.65%, type II 63.24%, type III 19.12%). The morphologic manifestation of pleural pathology by HRCT could be classified into four types: (1) nodular type: 73.38%, (2) flat type: 18.71%, (3) irregular type: 7.91%, (4) mixed type. The pleural pathological changes were found in thoracic wall pleura (65.02%), surface of mediastinum (22.16%), and pericardium (12.80%), but not found in the top of lung and costo-phrenic angles. The thickness of pleura was often about 5 approximately 10 mm (88.17%). CONCLUSION: Pleural pathological changes were not seldom seen in coal miner's pneumoconiosis. HRCT is a reliable examination method aiding routine CT to show pleural pathological changes, thus it has a great diagnostic and practical value. It is necessary to make a further comparison study between pathology and imagology.

[CT quantitative study of coal miner's pneumoconiosis].

OBJECTIVE: To study the value of CT quantitativeness in the diagnosis of coal miner's pneumoconiosis. METHODS: 104 cases were examined by HRCT scan at top of aortic arc, carina of trachea, 3 cm below the bifurcation of bronchi, among them there were 87 patients with different stages of coal miner's pneumoconiosis, 17 cases of normal males as the control group. All images were determined by CT density histogram at specific region (- 1,024-0 HU). Calculated the percentage of each pixel included a varying number of CT value, and the ratio of density values in the specific region. RESULTS: The ratio of density values in the region of -983 (-) -778 HU was 87.31% in normal control group, and 80.51%, 75.27% and 72.99% respectively in the I, II, III stages of coal miner's pneumoconiosis. There were statistically significant differences among the groups (P < 0.01). CONCLUSION: CT quantitative histogram information was able to observe the fibrosis and its degree of coal miner's pneumoconiosis. It has a good diagnostic value for its reliability and objectiveness.