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Amorphous gallium oxide (a-GaO x) thin films are fabricated via magnetron sputtering at room temperature by regulating the substrate bias voltage (V s) in a wide range (0 ~ -184 V). The effect of V s on the performance of a-GaO x films and their photodetector devices, such as the chemical composition, optical, morphological, and electrical properties, are systematically investigated. It's found that both the refractive index and the film relative mass density are highly dependent on the Ga/O ratio that can be effectively modified by the V s. And the subband trap density or/and microvoid defects in a-GaO x films can be largely reduced under a well-selected V s. The deep-ultraviolet photodetectors based on the optimized a-GaO x thin films show a responsivity of nearly 13 A/W with an ultrahigh UV/vis. rejection ratio. The research suggests that substrate bias voltage may be a feasibly subsidiary method for low-temperature magnetron sputtering technology with respect to the quality control of a-GaO x films. [ABSTRACT FROM AUTHOR]

Dielectrics fabrication on rough substrates, always leading to microstructural defects and detrimental dielectric properties eventually, is a great challenge for academic endeavors in this field. We report here on self-flattening AlO x :Y dielectric thin films processed by a facile aqueous solution method. The obtained AlO x :Y dielectrics are dense, large-area uniform, and amenable to accurate control of film thickness by repeating the deposition cycles. In particular, an atomically smooth surface with a RMS of 0.10 nm was realized for the AlO x :Y film with a thickness of 14.5 nm on Si wafer, yielding a low leakage current density of 7.9 × 10-8 A cm-2@2 MV/cm, a dielectric constant of 8.8 @100 Hz, and an attenuated dielectric dispersion property. The interactions between pre-baked YO x underlayer and later-dropped AlO x precursor were comprehensively investigated, in order to understand the film growth mechanism and the origin of self-flattening effect. Fortunately, this self-flattening effect is also applicable to other substrates. A RMS of 0.81 nm was achieved on ITO glasses, and the height distribution profile of the film surface was found to follow symmetric Gaussian distribution. This preparation routine was also examined by device verification in the fully-transparent thin-film transistors. The combination of ease of preparation and attractive physical properties would provide a green-route solution platform for dielectric synthesis, for interface engineering, and for well-performed devices on rough substrates. [ABSTRACT FROM AUTHOR]

Cermet-based solar selective absorbing coatings are widely used, however, the long-term thermal instability and pretty high infrared emissivity at high temperatures (>550 °C) are still challenging issues to be addressed, which essentially lies in suppressing the growing up and agglomeration behaviors of metal nanoparticles (NPs) and maintaining the interface integrity in the multi-layer stacked structure. Herein, we develop and explore WTi-Al 2 O 3 cermet-based absorbing coatings, demonstrating a solar absorptance of ~93% and a very low thermal emissivity of 10.3% @500 °C even after annealing at 600 °C for 840 h in vacuum. It is revealed that the surface segregation of solute Ti atoms from the parent alloyed NPs and their partial oxidation to form protective layer restrain outward diffusion of W element, agglomeration of NPs, and interface structure degradation, in favor of enhancing the thermal tolerance of the coatings. These results suggest that the WTi-Al 2 O 3 based absorbing coating is a good candidate for high-temperature solar thermal conversion. [ABSTRACT FROM AUTHOR]

The anisotropic carrier trapping behaviors was demonstrated for ambipolar tin monoxide (SnO) thin-film transistors (TFTs). On one hand, the TFTs exhibited good stability with almost no changes in transfer characteristics under negative gate-bias stress (NGBS). On the other, under positive gate-bias stress (PGBS), the transfer curves presented parallel and positive shift with no degradation in field-effect mobility and subthreshold voltage swing. The stress-time evolution of the turn-on voltage shift, induced by different positive stress voltages and temperatures, could be described by the stretched exponential model. The relaxation time was extracted to be 1.6 × 10 4 s at room temperature with activation energy of 0.43 eV, indicating that the ambipolar SnO TFTs under PGBS approach the stability of amorphous indium-gallium-zinc oxide based TFTs. [ABSTRACT FROM AUTHOR]

Today, the earnest need for earth-abundant and environmentally friendly thermoelectric materials has revealed the importance of semiconductor metal oxides in order to eliminate the barrier towards their wide-ranging use in industrial applications. In the present work, we demonstrate the synthesis of p-type tin oxide thin films on quartz glass and Si substrates by using electron beam evaporation technique followed by rapid thermal annealing process at 200 °C for 20 min in Ar-atmosphere. Annealing-induced structural, electrical, optical and thermoelectric properties of pristine and annealed SnO thin films are primarily studied. The compositional and structural analysis of SnO films are performed by using X-Ray Diffraction, Scanning Electron Microscope as well as Atomic Force Microscope. Moreover, the mechanism of thermoelectric transportation at different measurement temperatures is deeply inspected via thermoelectric measurements. The Seebeck coefficient, carrier concentration and hole mobility in conjunction with the development of thin film nanostructures are discussed, predominantly. The optimal annealing may tune structural, electro-optic and thermoelectric properties of SnO films for the commercial-level maturity of thermoelectric devices for energy applications. • Synthesis of high quality p-type SnO thin films by e-beam evaporation method. • Phase stability can be achieved by optimal annealing of tin oxide thin films. • Electrical resistivity and mobility affects the thermoelectric properties. • Optimal annealing reduces the crystal imperfections and band-tail states in SnO films. • The air-annealing induces the phase transition in SnO x thin films. [ABSTRACT FROM AUTHOR]

We report a facile and low-temperature aqueous route for the fabrication of various oxide thin films (Al 2 O 3 , In 2 O 3 and InZnO). A detail study is carried out to reveal the formation and properties of these sol-gel-derived thin films. The results show that the water-based oxide thin films undergo the decomposition of nitrate group as well as conversion of metal hydroxides to form metal oxide framework. High quality oxide thin film could be achieved at low temperature by this aqueous route. Furthermore, these oxide thin films are integrated to form thin-film transistors (TFTs) and the electrical performance is systematically studied. In particular, we successfully demonstrate In 2 O 3 /Al 2 O 3 TFTs with high mobility of 30.88 cm 2 V −1 s −1 and low operation voltage of 4 V at a maximum processing temperature of 250 °C. [ABSTRACT FROM AUTHOR]

Purpose: We sought to evaluate the performance of a new "one-stop-shop" scan protocol combining brain computed tomography perfusion (CTP) and head-and-neck CT angiography (CTA) imaging for acute stroke patients using a 256-detector CT scanner.Method: From March to August 2020, 60 patients (30 men and 30 women) aged 22-88 years with suspected acute stroke were enrolled and randomly divided into 2 groups to undergo brain CTP and head-and-neck CTA with a 256-detector CT system. Group A used traditional scan protocol with a separate brain CTP and head-and-neck CT examination that included non-contrast-enhanced and contrast-enhanced acquisitions; group B used the new "one-stop-shop" scan protocol with head-and-neck CTA data inserted into brain CTP scans at the peak time (PT) of the arterial phase. The insertion point of the head-and-neck CTA data was determined by a test bolus. The examination time, contrast dose, radiation dose, and image quality were compared between the groups.Results: The total contrast dose was reduced by 40% in group B compared to group A (60 mL vs. 100 mL). The imaging time was 52.5 ± 2.6 s in group B and 74.9 ± 3.3 s in group A, showing a reduction of approximately 43% in group B. There was no significant difference in image quality both quantitatively and qualitatively between the groups (all P > 0.05). Group B had a slight reduction in dose length product (1139.0 ± 45.3 vs. 1211.6 ± 31.9 mGy·cm, P < 0.001).Conclusions: The proposed "one-stop-shop" scan protocol combining brain CTP and head-and-neck CTA on a 256-detector CT system can reduce imaging time and contrast dose, without affecting image quality or perfusion results, compared to the traditional protocol of separating the examinations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis of high quality p-type SnO thin films by e-beam evaporation method. • Post deposition heat treatment of SnO x films at temperature (300–700 °C). • Optimal annealing reduces the crystal imperfections and band-tail states in SnO films. • Study of temperature-dependent morphology evolution for preferred crystal growth. In the present work, we demonstrate the growth of tin oxide (SnO x) thin films using electron beam evaporation method to study the phase transition from stannous oxide (SnO) to stannic oxide (SnO 2) by varying annealing temperature (i.e., from 300 to 700 °C). Annealing induced morphology evolution and structural modifications stimulate the process of phase-transformation, which is primarily discussed by divided the entire temperature range into two-regimes. Regime-A (from 300 to 400 °C) consists of tetragonal α-SnO dominated phase, regime-B (from 600 to 700 °C) exhibits orthorhombic pure SnO 2 phase. However, these regimes are being separated by an interface conferring a mixed-phase of tin oxides at an annealing temperature ∼500 °C. This temperature-dependent phase-inversion is adequately controlled by tuning the morphological, structural and optical properties of SnO x thin films to develop homo/heterostructures for various photovoltaic and optoelectronic applications. [ABSTRACT FROM AUTHOR]

Abstract: An amorphous carbon thin film, with through-pores of several tens of nanometers in size, has been synthesized by annealing magnetron sputtered nitrogen-doped carbon thin films at elevated temperature in an inert atmosphere. Based on this nanoporous carbon film, we first report forming-free resistive switching in a two terminal device containing ready-made metal nanofilaments. Such nanoporous carbon-based resistance memory device shows low operation voltages and good endurance and retention performance. [Copyright &y& Elsevier]

[Display omitted] • The abnormal local and long-range FCD in MCI compared with HCs. • The reversed FCD was found in MCI after treatments of acupoint-related moxibustion. • After moxibustion treatment, the MoCA scores of MCI were improved. Mild cognitive impairment (MCI) is a general neurodegenerative disease. Moxibustion has been shown to have remarkable effect on cognitive improvement, however, less is known about the effect of moxibustion on MCI and its underlying neural mechanism. This study aimed to investigate the ameliorative brain network in MCI after treatments of acupoint-related moxibustion. Resting-state functional MRI were derived from 47 MCI patients and 30 healthy controls (HCs). Patients were randomized as Tiaoshen YiZhi (TSYZ, n = 27) and sham (SHAM, n = 20) acupoint moxibustion groups. Functional connectivity density (FCD) method and repeated-measures two-way analysis of variance (ANOVA) were performed to ascertain the interaction effects between groups (TSYZ and SHAM) and time (baseline and post-treatment). Abnormal FCD was examined between baseline and post-treatment in TSYZ and SHAM groups, respectively. Compared with HCs, MCI showed altered FCD in the middle frontal cortex (MFC), inferior frontal cortex, temporal pole, thalamus and middle cingulate cortex. After moxibustion treatment in MCI, 1) a significant time-by-groups interaction was observed in the medial prefrontal cortex (mPFC); 2) abnormal long-range FCD (lrFCD) in the mPFC and MFC were modulated in TSYZ group; 3) significantly improved clinical symptoms; 4) changed lrFCD in the MFC was significantly negatively correlated with the increased Montreal Cognitive Assessment scores in TSYZ group. These imaging findings suggest that treatments of acupoint-related moxibustion could improve lrFCD in certain regions related to self-related cognitive and decision making. Our study might promote understanding of MCI neural mechanisms and expand the clinical application of moxibustion in MCI. [ABSTRACT FROM AUTHOR]

• An new multi-task learning framework is devised for differential diagnosis of subjective cognitive decline and mild cognive impairment. • The proposed multi-task learning algorithm combines functional and structural brain information. • The proposed method can discover the most disease-related brain regions and their connectivity. • The extensive experiments demonstrate good classification performance against competing techniques. Early diagnosis and intervention of mild cognitive impairment (MCI) and its early stage (i.e., subjective cognitive decline (SCD)) is able to delay or reverse the disease progression. However, discrimination between SCD, MCI and healthy subjects accurately remains challenging. This paper proposes an auto-weighted centralised multi-task (AWCMT) learning framework for differential diagnosis of SCD and MCI. AWCMT is based on structural and functional connectivity information inferred from magnetic resonance imaging (MRI). To be specific, we devise a novel multi-task learning algorithm to combine neuroimaging functional and structural connective information. We construct a functional brain network through a sparse and low-rank machine learning method, and also a structural brain network via fibre bundle tracking. Those two networks are constructed separately and independently. Multi-task learning is then used to identify features integration of functional and structural connectivity. Hence, we can learn each task's significance automatically in a balanced way. By combining the functional and structural information, the most informative features of SCD and MCI are obtained for diagnosis. The extensive experiments on the public and self-collected datasets demonstrate that the proposed algorithm obtains better performance in classifying SCD, MCI and healthy people than traditional algorithms. The newly proposed method has good interpretability as it is able to discover the most disease-related brain regions and their connectivity. The results agree well with current clinical findings and provide new insights into early AD detection based on the multi-modal neuroimaging technique. [Display omitted] [ABSTRACT FROM AUTHOR]

A solar selective absorber coating of CrN x O y /SiO2 was prepared on Cu (Si) substrate using DC reactive magnetron sputtering technique. The coating exhibits a high absorptivity (α) of 0.947 and a low emissivity (ε) of 0.05 at 80°C. The spectral selectivity (α/ε) of the coating on Cu substrate is stable (0.930/0.073) even after heat-treatment at 278°C in air for 300h, but decreased (0.904/0.135) at 278°C for 600h. The determinants to govern the thermal stability were investigated by micro-Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) measurements, which reveal that the element diffusion whether throughout all the stacked layers or near the interface region, the chemical interactions adjacent to the interface, and the interface width broadening are the Achilles' heel for the solar thermal coatings to sustain high thermal stability. [ABSTRACT FROM AUTHOR]

The block copolymer (BCP) templates with nanoscale structures and diverse morphologies have attracted much attention for nanofabrication in photonic and plasmonic research fields. Herein, PS-b-PMMA BCP nanotemplates with different morphologies, including the patterns of hexagonal hole arrays, fingerprint stripes, and their mixture, are successfully prepared for in-depth microstructural and optical characterizations. Apart from direct microstructure observations and component characterization, ellipsometric measurements are mainly applied to characterize structural and optical evolution of these BCP nanotemplates undergoing different preparation stages. Interestingly, among different BCP nanotemplates, two typical reflectance peaks in the ultraviolet region (200–250 nm) are distinctly different from each other, due to their PS- and thickness-dependent optical behaviors. With the preparation proceeding, there are synchronous diminution in the intensity of the two peaks, accompanying with an obvious blue-shift for the shorter wavelength peak. In addition, the variation of refractive index and ellipsometric parameters greatly demonstrates morphology-dependent optical behaviors among different BCP nanotemplates. Finally, Au-covered BCP nanotemplates present the distinct template-morphology-dependent visible-light responses, demonstrating different light-matter interactions occurred in their plasmonic Au nanostructures. • The structural and optical features of BCP templates were in-depth studied. • The optical changes of BCP templates with different treatments were investigated. • Ellipsometry was used to discern the morphological discrepancy of BCP templates. [ABSTRACT FROM AUTHOR]

Lithium-ion migration at the WO 3 /electrolyte interface is governed by the phase transformation mechanism by which metastable states are replaced from one phase to another. Herein, an in situ single nanowire-based cell is constructed to investigate the dynamic phase transformation and morphology evolution of h-WO 3 nanowire in real-time during its deep lithiation. One of the most significant features of h-WO 3 lithiation is the irreversible transformation from h-WO 3 to Li 2 WO 4. There are a large number of deep ion-trapping sites composed of 4 O atoms in Li 2 WO 4 crystal structure, that is, inserted lithium ions are irreversibly bound in these traps and nearly cannot be deintercalated. A mechanism on irreversible WO 3 -to-Li 2 WO 4 transformation in deep lithiation reaction is demonstrated. With the aid of in situ transmission electron microscopy, we controllably triggered lithium-ion migration at the WO 3 /electrolyte interface and directly visualized the nanoscale lithium-ion migration as a stop motion movie. Hexagonal WO 3 irreversible transformation to Li 2 WO 4 can be experimentally demonstrated via in situ HRTEM in the deep lithiation process including the initial activation of the lithium metal, the wetting of a single WO 3 nanowire and the migration of lithium ions into WO 3 , and the restructuring of hexagonal WO 3. [Display omitted] [ABSTRACT FROM AUTHOR]